U.S. patent application number 13/221868 was filed with the patent office on 2012-03-01 for robot, robot system, robot control device, and state determining method.
This patent application is currently assigned to KABUSHIKI KAISHA YASKAWA DENKI. Invention is credited to Shingo Ando, Takuya Fukuda, Yukio HASHIGUCHI, Takeomi Hidaka, Shinji Murai, Takenori Oka, Manabu Okahisa.
Application Number | 20120048027 13/221868 |
Document ID | / |
Family ID | 44719312 |
Filed Date | 2012-03-01 |
United States Patent
Application |
20120048027 |
Kind Code |
A1 |
HASHIGUCHI; Yukio ; et
al. |
March 1, 2012 |
ROBOT, ROBOT SYSTEM, ROBOT CONTROL DEVICE, AND STATE DETERMINING
METHOD
Abstract
A robot according to an embodiment includes arm and a strain
sensor. The strain sensor includes a piezoelectric body that has a
natural frequency higher than a natural frequency of a structural
material forming the arm.
Inventors: |
HASHIGUCHI; Yukio; (Fukuoka,
JP) ; Ando; Shingo; (Fukuoka, JP) ; Fukuda;
Takuya; (Fukuoka, JP) ; Oka; Takenori;
(Fukuoka, JP) ; Murai; Shinji; (Fukuoka, JP)
; Hidaka; Takeomi; (Fukuoka, JP) ; Okahisa;
Manabu; (Fukuoka, JP) |
Assignee: |
KABUSHIKI KAISHA YASKAWA
DENKI
Kitakyushu-shi
JP
|
Family ID: |
44719312 |
Appl. No.: |
13/221868 |
Filed: |
August 30, 2011 |
Current U.S.
Class: |
73/763 ;
901/27 |
Current CPC
Class: |
B25J 13/085 20130101;
B25J 9/1633 20130101; B25J 9/0087 20130101 |
Class at
Publication: |
73/763 ;
901/27 |
International
Class: |
G01L 1/16 20060101
G01L001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2010 |
JP |
2010-193717 |
Aug 31, 2010 |
JP |
2010-193718 |
Dec 28, 2010 |
JP |
2010-293843 |
Dec 28, 2010 |
JP |
2010-293844 |
Dec 28, 2010 |
JP |
2010-293845 |
Dec 28, 2010 |
JP |
2010-293846 |
Claims
1. A robot comprising: an arm; and a strain sensor that includes a
piezoelectric body with a natural frequency higher than a natural
frequency of a structure material forming the arm.
2. The robot according to claim 1, further comprising: one or more
actuators that are provided in the arm and drive the arm; and a
sensor fixing jig that is provided in a base of the actuator, among
the actuators in the arm, closest to a base end of the arm, wherein
the strain sensor is provided in the sensor fixing jig.
3. The robot according to claim 2, wherein the sensor fixing jig is
provided in a casing of the arm or a casing of the robot.
4. The robot according to claim 3, wherein the at least three
strain sensors are radially disposed on the same circumference at
an equal interval.
5. The robot according to claim 1, wherein the arm include one or
more actuators, and the strain sensor is provided as a first strain
sensor in the vicinity of a front end of a casing of the arm.
6. The robot according to claim 5, further comprising: an A/D
converter that is provided in the vicinity of the first strain
sensor and converts an output signal of the first strain sensor
into a digital signal.
7. The robot according to claim 5, wherein the first strain sensor
is provided on an external surface of the casing.
8. A robot system comprising: a robot that includes arm; a strain
sensor that includes a piezoelectric body with a natural frequency
higher than a natural frequency of a structure material forming the
arm; and a control unit that determines a predetermined state of
the robot, on the basis of an output value of the strain
sensor.
9. The robot system according to claim 8, wherein the control unit
includes a determining unit that determines whether the robot is in
a normal state or an abnormal state, on the basis of the output
value of the strain sensor.
10. The robot system according to claim 9, wherein the control unit
further includes a normative data recording unit that records a
time history of the output value of the strain sensor while the arm
execute a predetermined operation at the time of the normal state
as normative data, and the determining unit compares output data of
the output value of the strain sensor when the arm execute the
predetermined operation at the time of activating with the
normative data recorded in the normative data recording unit, and
determines whether the robot is in the normal state or the abnormal
state.
11. The robot system according to claim 10, wherein the determining
unit determines that the robot is in the normal state, when the
difference between the output data and the normative data is within
a range of a predetermined threshold value, and determines that the
robot is in the abnormal state, when the difference exceeds the
threshold value.
12. The robot system according to claim 8, wherein the control unit
includes: a normative data recording unit that records a time
history of the output value of the strain sensor while the arm
execute a predetermined operation in a state where there is no
abnormality as normative data, an output data recording unit that
records a time history of an output value of the strain sensor
while the arm execute the predetermined operation at the time of
activating as output data, and a comparing/determining unit that
compares the normative data recorded in the normative data
recording unit with the output data recorded in the output data
recording unit and determines whether there is abnormality in the
arm.
13. The robot system according to claim 12, wherein one or more
actuators that cause one or more joint portions included in the arm
to operate are provided in the arm, and the comparing/determining
unit determines that there is abnormality in the actuators, when an
event where a difference between the output data and the normative
data exceeds a predetermined threshold value occurs for every
predetermined cycle.
14. The robot system according to claim 12, wherein the
comparing/determining unit determines that there is abnormality in
the robot arm, when the number of times of excess where the
difference between the output data and the normative data exceeds a
predetermined threshold value in a predetermined time period
exceeds a predetermined number of times of determination.
15. A robot system comprising: a robot arm; one or more actuators
that are provided in the robot arm and drive the robot arm; a
sensor unit that detects an external force applied to at least one
of the robot arm and the actuators; and a controller that controls
an operation of each of the actuators and limits a torque
instruction value with respect to each of the actuators, on the
basis of a result of the detection by the sensor unit.
16. A robot system comprising: a manipulator that includes one or
more actuators; and a controller that controls driving of each of
the actuators, wherein the controller includes: a target
position/posture generating unit that sets a target
position/posture of the manipulator; a simulation unit that
generates an operation trace until the manipulator reaches from a
current posture to the target position/posture, on the basis of the
target position/posture; a redundant angle definition table in
which small regions set by dividing a region within a reachable
range of the manipulator, and parameters for redundant axis angles
corresponding to the small regions are associated with each other;
a region determining unit that selects the corresponding small
region in the redundant angle definition table, on the basis of the
output result of the target position/posture generating unit; a
redundant axis angle setting unit that sets a redundant axis angle
which is an angular position of a part of the actuators, on the
basis of the selection result of the region determining unit and
the redundant angle definition table; and an interpolation
operating unit that generates an operation instruction with respect
to each of the actuators, on the basis of the operation trace and
the redundant axis angle.
17. A control device of a robot including a robot arm that includes
one or more actuators, and a sensor unit that detects an external
force applied to at least one of the robot arm and the actuators,
the control device comprising: an actuator control unit that
transmits a torque instruction to the actuator; and a torque
instruction limiting unit that limits a value of the torque
instruction transmitted to the actuator, on the basis of the result
from the sensor unit which is input.
18. A robot control device that controls an operation of a
manipulator including one or more actuators, the robot control
device comprising: a target position/posture generating unit that
sets a target position/posture of the manipulator, a simulation
unit that generates an operation trace until the manipulator
reaches from a current posture to the target position/posture, on
the basis of the target position/posture, a redundant angle
definition table in which small regions set by dividing a region
within a reachable range of the manipulator, and parameters for
redundant axis angles corresponding to the small regions are
associated with each other, a region determining unit that selects
the corresponding small region in the redundant angle definition
table, on the basis of the output result of the target
position/posture generating unit, a redundant axis angle setting
unit that sets the redundant axis angle that is an angular position
of a part of the actuators, on the basis of the selection result of
the region determining unit and the redundant angle definition
table, and an interpolation operating unit that generates an
operation instruction with respect to each of the actuators, on the
basis of the operation trace and the redundant axis angle.
19. A state determining method using a robot having a robot arm,
the state determining method comprising: acquiring an output value
of a strain sensor that has a piezoelectric body with a natural
frequency higher than a natural frequency of a structural material
forming the robot arm; and determining a predetermined state of the
robot, on the basis of an output value of the strain sensor.
20. A robot, comprising: a robot arm; and a means for detecting
dynamic strain of a structural material forming the robot arm.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2010-193717, filed on Aug. 31, 2010; Japanese Patent Application
No. 2010-193718, filed on Aug. 31, 2010; Japanese Patent
Application No. 2010-293843, filed on Dec. 28, 2010; Japanese
Patent Application No. 2010-293844, filed on Dec. 28, 2010;
Japanese Patent Application No. 2010-293845, filed on Dec. 28,
2010; and Japanese Patent Application No. 2010-293846, filed on
Dec. 28, 2010, the entire contents of all of which are incorporated
herein by reference.
FIELD
[0002] The embodiments discussed in the present application are
directed to a robot, a robot system, a robot control device, and a
state determining method.
BACKGROUND
[0003] From the past, in the field of robotics, it is preferable to
prevent an excessive load from acting on a robot or an object
existing around the robot. For this reason, various technologies
for detecting generation or non-generation of a contact (external
force) to the robot are studied. For example, a technology is known
which installs a force detector in a base end of a robot arm to
detect the external force, and stops an operation of the robot arm
on the basis of the detection result of the force detector or
causing the robot arm to move in the direction capable of reducing
the effect of the external force when the excessive external force
is applied. The relevant technologies of the related art are
described, for example, in Japanese Patent Application Laid-Open
(JP-A) Nos. 2006-21287 and 2007-203380.
[0004] However, in the related art in which the force detector is
simply provided in the robot, the response of the force detector to
the contact of the robot arm is late, which may become an obstacle
in detecting a light or momentary touch with a high degree of
precision and improving the functionality of the robot.
SUMMARY
[0005] A robot according to an aspect of the embodiment includes a
robot arm and a strain sensor. The strain sensor includes a
piezoelectric body that has a natural frequency higher than that of
a structural material forming the robot arm.
BRIEF DESCRIPTION OF DRAWINGS
[0006] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0007] FIG. 1 is a conceptual diagram illustrating the entire
configuration of a robot system that includes a robot according to
a first embodiment.
[0008] FIG. 2 is a top view illustrating the configuration of the
robot according to the first embodiment.
[0009] FIG. 3 is a block diagram illustrating the functional
configuration of a robot controller according to the first
embodiment.
[0010] FIG. 4 is a block diagram illustrating the functional
configuration of an abnormality detecting unit according to the
first embodiment.
[0011] FIG. 5 is a diagram illustrating the detailed configuration
of sensor units, a high-pass filter unit, and a
comparing/determining unit according to the first embodiment.
[0012] FIGS. 6A and 6B are diagrams illustrating a predetermined
operation that is executed by arms according to the first
embodiment in a state in which there is no abnormality and an
output value of a sensor of a sensor during the predetermined
operation.
[0013] FIGS. 7A and 7B are diagrams illustrating a predetermined
operation that is executed by the arms according to the first
embodiment at the time of activating and an output value of the
sensor during the predetermined operation.
[0014] FIGS. 8A and 8B are diagrams illustrating an example of a
method of detecting whether there is abnormality in the arms
according to the first embodiment.
[0015] FIG. 9 is a flowchart illustrating a control sequence that
is executed by the robot controller according to the first
embodiment.
[0016] FIG. 10 is a schematic view illustrating a predetermined
operation that is executed by the arms at the time of activating,
in a modification that is applied to detection of a contact of an
object.
[0017] FIG. 11 is a conceptual diagram illustrating the entire
configuration of a robot system that includes a robot according to
a second embodiment.
[0018] FIG. 12 is a top view illustrating the configuration of the
robot according to the second embodiment.
[0019] FIG. 13 is a diagram illustrating an inspected object
according to the second embodiment.
[0020] FIG. 14 is a block diagram illustrating the functional
configuration of a robot controller according to the second
embodiment.
[0021] FIG. 15 is a block diagram illustrating the functional
configuration of an abnormality detecting unit according to the
second embodiment.
[0022] FIG. 16 is a diagram illustrating an output value V of a
sensor when arms according to the second embodiment execute a
predetermined operation with respect to an inspected object in
which there is no abnormality.
[0023] FIG. 17 is a diagram illustrating an output value V of a
sensor when the arm according to the second embodiment executes a
predetermined operation with respect to the inspected object, at
the time of activating.
[0024] FIGS. 18A and 18B are diagrams illustrating an example of a
method of detecting whether there is abnormality in the inspected
object according to the second embodiment.
[0025] FIG. 19 is a flowchart illustrating a control sequence that
is executed by the robot controller according to the second
embodiment.
[0026] FIG. 20 is a top view illustrating the configuration of a
robot according to a modification that is applied to detection of a
contact of an object.
[0027] FIG. 21 is a schematic diagram illustrating an example of a
predetermined operation that is executed by the arms with respect
to the inspected object, at the time of inspecting.
[0028] FIG. 22 is a conceptual diagram illustrating the entire
configuration of a robot system according to a third
embodiment.
[0029] FIG. 23 is a top view illustrating the configuration of the
robot according to the third embodiment.
[0030] FIG. 24 is a block diagram illustrating the functional
configuration of a robot controller according to the third
embodiment.
[0031] FIG. 25 is a block diagram illustrating the functional
configuration of a contact detecting unit according to the third
embodiment.
[0032] FIG. 26 is a diagram illustrating the detailed configuration
of sensor units, a high-pass filter unit, and a determining unit
according to the third embodiment.
[0033] FIGS. 27A and 27B are diagrams illustrating a predetermined
operation that is executed by arms according to the third
embodiment in a state in which an object does not contact the arm
and an output value of a sensor during the predetermined
operation.
[0034] FIGS. 28A and 28B are diagrams illustrating a predetermined
operation that is executed by the arms according to the third
embodiment at the time of activating and an output value of a
sensor during the predetermined operation
[0035] FIGS. 29A and 29B are diagrams illustrating a method of
detecting whether the object contacts the arms according to the
third embodiment.
[0036] FIG. 30 is a flowchart illustrating a control sequence of a
state determining method of the robot that is executed by the robot
controller according to the third embodiment.
[0037] FIG. 31 is a schematic view illustrating a predetermined
operation that is executed by the arm at the time of activating, in
a modification that is applied to detection of a contact of an
obstacle.
[0038] FIG. 32 is a conceptual diagram illustrating the entire
configuration of a robot system according to a fourth
embodiment.
[0039] FIG. 33 is a top view illustrating the configuration of the
robot according to the fourth embodiment.
[0040] FIG. 34 is a block diagram illustrating the functional
configuration of a robot controller according to the fourth
embodiment.
[0041] FIG. 35 is a block diagram illustrating the functional
configuration of an abnormality detecting unit according to the
fourth embodiment.
[0042] FIG. 36 is a diagram illustrating the detailed configuration
of sensor units, a high-pass filter unit, and a
comparing/determining unit according to the fourth embodiment.
[0043] FIGS. 37A and 37B are diagrams illustrating a predetermined
operation that is executed by arms according to the fourth
embodiment in a state in which there is no abnormality and an
output value V of a sensor during the predetermined operation.
[0044] FIGS. 38A and 38B are diagrams illustrating a predetermined
operation that is executed by the arms according to the fourth
embodiment at the time of activating and an output value V of a
sensor during the predetermined operation
[0045] FIGS. 39A and 39B are diagrams illustrating an example of a
method of detecting whether there is abnormality in the arms
according to the fourth embodiment.
[0046] FIG. 40 is a flowchart illustrating a control sequence of an
abnormality detecting method of the robot that is executed by the
robot controller according to the fourth embodiment.
[0047] FIG. 41 is a schematic view illustrating a predetermined
operation that is executed by the arms at the time of activating,
in a modification that is applied to detection of a contact of an
object.
[0048] FIG. 42 is a schematic diagram illustrating the entire
configuration of a robot system according to a fifth
embodiment.
[0049] FIG. 43 is a side view illustrating the configuration of a
robot according to the fifth embodiment.
[0050] FIG. 44 is a schematic diagram illustrating the
configuration of a sensor unit according to the fifth
embodiment.
[0051] FIG. 45 is a block diagram illustrating the functional
configuration of a contact detecting unit according to the fifth
embodiment.
[0052] FIG. 46 is a block diagram illustrating the functional
configuration of an external force direction detecting unit
according to the fifth embodiment.
[0053] FIG. 47 is a schematic view illustrating table data
according to the fifth embodiment.
[0054] FIG. 48 is a diagram illustrating an arrangement
relationship of sensors and external force direction vectors
according to the fifth embodiment.
[0055] FIG. 49 is a block diagram illustrating the functional
configuration of an avoidance axis selecting unit according to the
fifth embodiment.
[0056] FIG. 50 is a block diagram illustrating the functional
configuration of an avoidance compensating unit according to the
fifth embodiment.
[0057] FIG. 51 is a chart illustrating a function of a torque
limiting unit according to the fifth embodiment.
[0058] FIG. 52 is a block diagram illustrating a contact detecting
unit according to a sixth embodiment.
[0059] FIG. 53 is a block diagram illustrating an external force
direction detecting unit according to the sixth embodiment.
[0060] FIG. 54 is a diagram illustrating an example of a signal
integration processing result according to the sixth
embodiment.
[0061] FIG. 55 is a diagram illustrating an example of an external
force direction narrowing condition table according to the sixth
embodiment.
[0062] FIG. 56 is a diagram illustrating an example of external
force direction narrowing processing according to the sixth
embodiment.
[0063] FIG. 57 is a schematic diagram illustrating the entire
configuration of a robot system according to a seventh
embodiment.
[0064] FIG. 58 is a schematic diagram illustrating the entire
configuration of a robot system according to an eighth
embodiment.
[0065] FIG. 59 is a side view illustrating the configuration of a
robot according to the eighth embodiment.
[0066] FIG. 60 is a schematic diagram illustrating the
configuration of a sensor unit according to the eighth
embodiment.
[0067] FIG. 61 is a schematic diagram illustrating a region of a
three-dimensional space that is defined in a redundant angle
definition table according to the eighth embodiment.
[0068] FIG. 62 is a schematic diagram illustrating a coordinate
relationship of an end effector and a target portion (work object)
according to the eighth embodiment.
[0069] FIG. 63 is a diagram illustrating an example of the
redundant angle definition table according to the eighth
embodiment.
DESCRIPTION OF EMBODIMENTS
[0070] A robot according to an embodiment includes a robot arm and
a strain sensor. The strains sensor has a piezoelectric body that
has a natural frequency higher than that of a structural material
forming the robot arm.
[0071] A robot system according to an embodiment includes a robot,
a strain sensor, and a control unit. The robot has a robot arm. The
strains sensor has a piezoelectric body that has a natural
frequency higher than that of a structural material forming the
robot arm. The control unit determines a predetermined state of the
robot, on the basis of an output value of the strain sensor.
[0072] First, a first embodiment will be described.
[0073] In a field of robots, it is preferable to avoid an excessive
load from being generated with respect to a robot or an object
existing around the robot. For this reason, generation or
non-generation of a contact (external force) with respect to the
robot needs to be detected.
[0074] For example, a technology for attaching a force detector to
detect the external force to a base end of a robot arm and stopping
an operation of the robot arm on the basis of the detection result
of the force detector or operating the robot arm in a reduction
direction of the external force when the excessive external force
is applied is disclosed in JP-A No. 2006-21287.
[0075] In order to improve functionality of the robot, it is
preferable to detect generation or non-generation of a contact with
respect to the robot arm with high precision.
[0076] In the related art, a six-axis force sensor is used as the
force detector, and because the magnitude of the actual external
force applied to the robot arm is detected, responsiveness with
respect to the contact of the robot arm is late. Further, a slight
contact or a momentary contact may not be sufficiently
detected.
[0077] According to one aspect of the embodiment, a robot that can
improve functionality of the robot is provided.
[0078] According to this embodiment, the functionality of the robot
can be improved.
[0079] Hereinafter, the first embodiment will be described with
reference to the drawings. This embodiment is an example of the
case where the robot disclosed in the present application is
applied to detection of abnormality of robot arms.
[0080] FIG. 1 is a conceptual diagram illustrating the entire
configuration of a robot system that includes the robot according
to the first embodiment. FIG. 2 is a top view illustrating the
configuration of the robot according to the first embodiment.
[0081] In FIGS. 1 and 2, a robot system 1001 according to this
embodiment includes a robot 1100 that is provided on one side of a
belt conveyor 1002 to convey plural products P and a robot
controller 1150 that controls the robot 1100. The robot 1100 is a
dual-arm robot and has a base 1101, a trunk portion 1102, two arms
1103L and 1103R (robot arms), and two sensor units 1120L and 1120R
that function as a means for detecting dynamic strain of a
structural material forming the robot arms.
[0082] The base 1101 is fixed to a mounting surface (floor) by an
anchor bolt (not illustrated in the drawings). The trunk portion
1102 has a first joint portion in which an actuator Ac1001 driven
to rotate around a rotation axis Ax1001 is provided. The trunk
portion 1102 is disposed to rotate through the first joint portion
with respect to the base 1101 and rotates along a direction
approximately horizontal to the mounting surface by driving of the
actuator Ac1001 provided in the first joint portion. The trunk
portion 1102 supports the arms 1103L and 1103R that are configured
as separate objects, at one side (right side in FIGS. 1 and 2) and
the other side (left side in FIGS. 1 and 2), respectively.
[0083] The arm 1103L is a manipulator that is provided on one side
of the trunk portion 1102. The arm 1103L has a shoulder portion
1104L, an upper arm A portion 1105L, an upper arm B portion 1106L,
a lower arm portion 1107L, a wrist A portion 1108L, a wrist B
portion 1109L, a flange 1110L, a hand 1111L, and second to eighth
joint portions in which actuators Ac1002 to Ac1008 to drive
rotation of the individual portions are provided, respectively.
[0084] The shoulder portion 1104L is connected to the trunk portion
1102 to rotate through the second joint portion and rotates around
a rotation axis Ax1002 approximately horizontal to the mounting
surface by driving of the actuator Ac1002 provided in the second
joint portion. The upper arm A portion 1105L is connected to the
shoulder portion 1104L to rotate through the third joint portion
and rotates around a rotation axis Ax1003 orthogonal to the
rotation axis Ax1002 by driving of the actuator Ac1003 provided in
the third joint portion. The upper arm B portion 1106L is connected
to a front end of the upper arm A portion 1105L to rotate through
the fourth joint portion and rotates around a rotation axis Ax1004
orthogonal to the rotation axis Ax1003 by driving of the actuator
Ac1004 provided in the fourth joint portion. The lower arm portion
1107L is connected to the upper arm B portion 1106L to rotate
through the fifth joint portion and rotates around a rotation axis
Ax1005 orthogonal to the rotation axis Ax1004 by driving of the
actuator Ac1005 provided in the fifth joint portion. The wrist A
portion 1108L is connected to a front end of the lower arm portion
1107L to rotate through the sixth joint portion and rotates around
a rotation axis Ax1006 orthogonal to the rotation axis Ax1005 by
driving of the actuator Ac1006 provided in the sixth joint portion.
The wrist B portion 1109L is connected to the wrist A portion 1108L
to rotate through the seventh joint portion and rotates around a
rotation axis Ax1007 orthogonal to the rotation axis Ax1006 by
driving of the actuator Ac1007 provided in the seventh joint
portion. The flange 1110L is connected to a front end of the wrist
B portion 1109L to rotate through the eighth joint portion and
rotates around a rotation axis Ax1008 orthogonal to the rotation
axis Ax1007 by driving of the actuator Ac1008 provided in the
eighth joint portion. The hand 1111L is attached to a front end of
the flange 1110L and rotates according to the rotation of the
flange 1110L.
[0085] The arm 1103R is a manipulator that is provided on the other
side of the trunk portion 1102. Similar to the arm 1103L, the arm
1103R has a shoulder portion 1104R, an upper arm A portion 1105R,
an upper arm B portion 1106R, a lower arm portion 1107R, a wrist A
portion 1108R, a wrist B portion 1109R, a flange 1110R, a hand
1111R, and ninth to fifteenth joint portions in which actuators
Ac1009 to Ac1015 to drive rotation of the individual portions are
provided, respectively.
[0086] The shoulder portion 1104R is connected to the trunk portion
1102 to rotate through the ninth joint portion and rotates around a
rotation axis Ax1009 approximately horizontal to the mounting
surface by driving of the actuator Ac1009 provided in the ninth
joint portion. The upper arm A portion 1105R is connected to the
shoulder portion 1104R to rotate through the tenth joint portion
and rotates around a rotation axis Ax1010 orthogonal to the
rotation axis Ax1009 by driving of the actuator Ac1010 provided in
the tenth joint portion. The upper arm B portion 1106R is connected
to a front end of the upper arm A portion 1105R to rotate through
the eleventh joint portion and rotates around a rotation axis
Ax1011 orthogonal to the rotation axis Ax1010 by driving of the
actuator Ac1011 provided in the eleventh joint portion. The lower
arm portion 1107R is connected to the upper arm B portion 1106R to
rotate through the twelfth joint portion and rotates around a
rotation axis Ax1012 orthogonal to the rotation axis Ax1011 by
driving of the actuator Ac1012 provided in the twelfth joint
portion. The wrist A portion 1108R is connected to a front end of
the lower arm portion 1107R to rotate through the thirteenth joint
portion and rotates around a rotation axis Ax1013 orthogonal to the
rotation axis Ax1012 by driving of the actuator Ac1013 provided in
the thirteenth joint portion. The wrist B portion 1109R is
connected to the wrist A portion 1108R to rotate through the
fourteenth joint portion and rotates around a rotation axis Ax1014
orthogonal to the rotation axis Ax1013 by driving of the actuator
Ac1014 provided in the fourteenth joint portion. The flange 1110R
is connected to a front end of the wrist B portion 1109R to rotate
through the fifteenth joint portion and rotates around a rotation
axis Ax1015 orthogonal to the rotation axis Ax1014 by driving of
the actuator Ac1015 provided in the fifteenth joint portion. The
hand 1111R is attached to a front end of the flange 1110R and
rotates according to the rotation of the flange 1110R.
[0087] In this example, each of the arms 1103L and 1103R has seven
joint portions, that is, degrees of freedom of 7 (redundant degrees
of freedom). However, the degrees of freedom of each of the arms
1103L and 1103R are not limited to "7".
[0088] As structural materials that form the shoulder portions
1104L and 1104R, the upper arm A portions 1105L and 1105R, the
upper arm B portions 1106L and 1106R, the lower arm portions 1107L
and 1107R, the wrist A portions 1108L and 1108R, the wrist B
portions 1109L and 1109R, the flanges 1110L and 1110R, and the
hands 1111L and 1111R of the arms 1103L and 1103R, metallic
materials such as iron or aluminum are used.
[0089] As illustrated in FIG. 2, the trunk portion 1102 is formed
to protrude forward in a horizontal direction from the first joint
portion to the second and ninth joint portions, with respect to the
base 1101, such that the rotation axis Ax1001 of the first joint
portion and the rotation axiss Ax1002 and Ax1009 of the second and
ninth joint portions are offset by the length D1 in a direction
approximately horizontal to the mounting surface. Thereby, a space
of the lower side of the shoulder portions 1104L and 1104R can be
used as a work space, and a reachable range of the arms 1103L and
1103R can be enlarged by rotating the rotation axis Ax1001.
[0090] A shape of the upper arm B portion 1106R is set such that
the positions of the rotation axis Ax1001 of the eleventh joint
portion and the rotation axis Ax1012 of the twelfth joint portion
in plan view are offset by the length D2. A shape of the lower arm
portion 1107R is set such that the positions of the rotation axis
Ax1012 of the twelfth joint portion and the rotation axis Ax1013 of
the thirteenth joint portion in plan view are offset by the length
D3. When the rotation axis Ax1011 and the rotation axis Ax1013 take
an approximately horizontal posture, the offset length of the
rotation axis Ax1011 and the rotation axis Ax1013 becomes (D2+D3).
Thereby, when the twelfth joint portion corresponding to a human
"elbow" is bent, clearance of the upper arm A portion 1105R and the
upper arm B portion 1106R corresponding to a human "upper arm" and
the lower arm portion 1107R corresponding to a human "lower arm"
can be greatly secured. Even when the hand 1111R comes close to the
trunk portion 1102, a degree of freedom of the arm 1103R at the
time of an operation increases.
[0091] Although not clearly illustrated in FIG. 2, similar to the
arm 1103R, in the arm 1103L, a shape of the upper arm B portion
1106L is set such that the positions of the rotation axis Ax1004 of
the fourth joint portion and the rotation axis Ax1005 of the fifth
joint portion in upper view are offset by the length D2. A shape of
the lower arm portion 1107L is set such that the positions of the
rotation axis Ax1005 of the fifth joint portion and the rotation
axis Ax1006 of the sixth joint portion in upper view are offset by
the length D3. When the rotation axis Ax1004 and the rotation axis
Ax1006 take an approximately horizontal posture, the offset length
of the rotation axis Ax1004 and the rotation axis Ax1006 becomes
(D2+D3). As illustrated in FIG. 2, each of the sensor units 1120L
and 1120R includes a sensor fixing jig 1121 that is provided on the
inner side of a casing constituting an outer wall of the robot 1100
(in this example, casing constituting an outer wall of the trunk
portion 1102) and is formed in an annular shape and at least three
(in this example, three) sensors 1122 (strain sensors) that have an
approximately rectangular solid shape. The sensor fixing jig 1121
of the sensor unit 1120L is attached to a base of a stator of the
actuator Ac1002 of the arm 1103L that is closest to the side of a
base end, and the three sensors 1122 that are provided in the
sensor fixing jig 1121 can detect the force applied the arm 1103L
(in detail, amount of strain caused by a vibration due to the
impact force applied to the arm 1103L, not the magnitude of the
force). The sensor fixing jig 1121 of the sensor unit 1120R is
attached to a base of a stator of the actuator Ac1009 of the arm
1103R that is closest to the side of a base end, and the three
sensors 1122 that are provided in the sensor fixing jig 1121 can
detect the force applied the arm 1103R (in detail, amount of strain
caused by a vibration due to the impact force applied to the arm
1103R, not the magnitude of the force). The sensor units 1120L and
1120R will be described in detail below.
[0092] In this example, the sensor fixing jigs 1121 of the sensor
units 1120L and 1120R are provided in the inner side of the casing
of the trunk portion 1102. However, the embodiment is not limited
thereto, and the sensor fixing jigs 1121 may be provided in the
inner side of the casings of the arms 1103L and 1103R,
respectively. In this example, the three sensors 1122 are provided
in the sensor fixing jig 1121. However, the embodiment is not
limited thereto and four or more (for example, four or five)
sensors may be provided in the sensor fixing jig 1121.
[0093] In the robot 1100 that has the above-described
configuration, operations of individual driving portions that
include the actuators Ac1001 to Ac1015 are controlled by the robot
controller 1150, such that the arms 1103L and 1103R are operated
toward the inner side than both sides of the product P on the belt
conveyor 1002 and the product P is gripped by the hands 1111L and
1111R. Each of the actuators Ac1001 to Ac1015 is composed of a
decelerator-integrated servo motor that has a hollow portion where
a wiring line (not illustrated in the drawings) can be inserted,
and the rotation positions of the actuators Ac1001 to Ac1015 are
input as signals from encoders (not illustrated in the drawings)
incorporated in the actuators Ac1001 to Ac1015 to the robot
controller 1150 through the wiring line.
[0094] FIG. 3 is a block diagram illustrating the functional
configuration of the robot controller 1150 according to the first
embodiment.
[0095] In FIG. 3, the robot controller 1150 is composed of a
computer that includes an operator, a storage device, and an input
device (not illustrated in the drawings) and is connected to the
individual driving portions or the individual sensors 1122 of the
robot 1100 through the wiring line to communicate with each other.
The robot controller 1150 has an operation instructing unit 1151, a
position instruction intercepting unit 1152, a smoothing processing
unit 1153, a servo unit 1154, an abnormality detecting unit 1155, a
grip torque compensating unit 1156, and a gravity torque
compensating unit 1157.
[0096] The operation instructing unit 1151 calculates a position
instruction (operation instruction) with respect to each of the
actuators Ac1001 to Ac1015, on the basis of instruction information
(information indicating the operation start position and the
operation completion position) with respect to each of the arms
1103L and 1103R instructed through the input device, and pools the
position instruction to the smoothing processing unit 1153 through
the position instruction intercepting unit 1152.
[0097] The smoothing processing unit 1153 sequentially outputs the
pooled position instruction to the servo unit 1154, for every
predetermined operation cycle.
[0098] The servo unit 1154 has a joint angle feedback circuit Fp
based on a detection value of the encoder of each of the actuators
Ac1001 to Ac1015 and a joint angle feedback circuit Fv based on an
angular speed detection value obtained from the detection value of
the encoder of each of the actuators Ac1001 to Ac1015, for each of
the actuators Ac1001 to Ac1015. The servo unit 1154 generates a
torque instruction Tref with respect to each of the actuators
Ac1001 to Ac1015 for every predetermined operation cycle, on the
basis of the position instructions sequentially input by the
smoothing processing unit 1153, and outputs the torque
instruction.
[0099] The abnormality detecting unit 1155 detects generation or
non-generation based on aging of a rotation member such as the
actuators Ac1002 to Ac1015 provided in the arms 1103L and 1103R and
the decelerator, on the basis of an output value V (output signal)
of each sensor 1122 of the sensor units 1120L and 1120R. However,
the embodiment is not limited thereto and the abnormality detecting
unit 1155 may detect generation or non-generation of abnormality
(including abnormality based on aging of the rotation member such
as the actuators Ac1002 to Ac1015 or the decelerator or abnormality
of the casings of the arms 1103L and 1103R) of the arms 1103L and
1103R. The abnormality detecting unit 1155 will be described in
detail below.
[0100] When the abnormality of the actuators Ac1002 to Ac1015 of
the arms 1103L and 1103R is detected by the abnormality detecting
unit 1155, the position instruction intercepting unit 1152
intercepts an output of the position instruction from the operation
instructing unit 1151 to the smoothing processing unit 1153 and
intercepts the position instruction that is transmitted to the
servo unit 1154. If the position instruction transmitted to the
servo unit 1154 is intercepted, a value of the torque instruction
Tref that is output by the feedback decreases and the arms 1103L
and 1103R are quickly stopped.
[0101] The grip torque compensating unit 1156 adds the grip
compensation torque to grip the product P by the arms 1103L and
1103R to the torque instruction Tref with respect to each of the
actuators Ac1001 to Ac1015 generated by the servo unit 1154.
[0102] The gravity torque compensating unit 1157 adds the gravity
compensation torque corresponding to the self weight to the torque
instruction Tref with respect to each of the actuators Ac1001 to
Ac1015 generated by the servo unit 1154.
[0103] FIG. 4 is a block diagram illustrating the functional
configuration of the abnormality detecting unit 1155 according to
the first embodiment.
[0104] In FIG. 4, the abnormality detecting unit 1155 has a
high-pass filter unit 1161, a section setting unit 1162, a
normative waveform recording unit 1163, an output waveform
recording unit 1167, a comparing/determining unit 1164, a zero
point adjusting unit 1165, and a threshold value setting unit
1166.
[0105] The high-pass filter unit 1161 extracts a high frequency
vibration component of an output signal of each sensor 1122 to
remove a frequency component (for example, frequency component due
to disturbance) other than a frequency due to the abnormality of
the arms 1103L and 1103R, which is included in the output signal of
each sensor 1122 of the sensor units 1120L and 1120R. The high-pass
filter unit 1161 will be described in detail below.
[0106] The section setting unit 1162 sets a section where the
normative waveform recording unit 1163 records a time history of
the output value V of the sensor 1122 as a normative waveform, on
the basis of input information input by the input device
(hereinafter, simply referred to as "recording section").
[0107] The normative waveform recording unit 1163 records the time
history of the output value V of each sensor 1122 based on the high
frequency vibration component extracted by the high-pass filter
unit 1161 while the arms 1103L and 1103R execute a predetermined
operation corresponding to the recording section set by the section
setting unit 1162 in a state in which there is no abnormality in
the arms 1103L and 1103R as a normative waveform (refer to FIG. 6B
to be described below) for each sensor 1122. In this case, the
state in which there is no abnormality in the arms 1103L and 1103R
means a state in which there is no structural or functional defect
and failure in the casings (including the structure member, the
cover member, and the wiring line) of the arms 1103L and 1103R and
the actuators Ac1002 to Ac1015 provided in the arms 1103L and 1103R
or the decelerator and the casings of the arms and the actuators or
the decelerator are normally operated, and a contact or
interference not to be intended is not generated in the arms 1103L
and 1103R. For example, the state in which there is no abnormality
in the arms 1103L and 1103R means a state immediately after it is
checked that the casings of the arms 1103L and 1103R and the
actuators Ac1002 to Ac1015 provided in the arms 1103L and 1103R or
the decelerator are normally operated or a state at the time of
initial activating in which there is no initial defect. The
predetermined operation is an operation according to the position
instruction that is calculated by the operation instructing unit
1151 on the basis of the instruction information (information
indicating the operation start position and the operation
completion position) instructed through the input device.
[0108] The output waveform recording unit 1167 may record the time
history of the output value V of each sensor 1122 based on the high
frequency vibration component extracted by the high-pass filter
unit 1161 while the arms 1103L and 1103R execute the predetermined
operation as an output waveform (refer to FIG. 7B to be described
below) for each sensor 1122. In this embodiment, the output
waveform recording unit 1167 records the time history of the output
value V of each sensor 1122 while the arms 1103L and 1103R execute
the predetermined operation as the output waveform for each sensor
1122, when the product P to be a grip object does not exist in a
movable range at the time of activating (for example, immediately
after starting conveyance of the product P or at the time of
stopping the conveyance and performing checking). However, the
embodiment is not limited thereto and the output waveform recording
unit 1167 records the time history of the output value V of each
sensor 1122 while the arms 1103L and 1103R execute the
predetermined operation at the time of activating as an output
waveform for each sensor 1122, when the product P to be a grip
object exists in a movable range at the time of activating.
[0109] The threshold value setting unit 1166 sets a threshold value
Dth that becomes a determination value of generation or
non-generation of the abnormality in the comparing/determining unit
1164, on the basis of the input information input through the input
device.
[0110] The comparing/determining unit 1164 compares the normative
waveform recorded in the normative waveform recording unit 1163 for
each sensor 1122 and the output waveform recorded in the output
waveform recording unit 1167 for each sensor 1122, for each sensor
1122, and calculates the difference (in detail, absolute value of
the difference) "D" of the normative waveform and the output
waveform, for each sensor 1122. The number of times (hereinafter,
referred to as number of times of excess N) where the difference
"D" calculated for each sensor 1122 exceeds a threshold value Dth
previously set by the threshold value setting unit 1166 for a
constant time (in this example, time needed when the arms 1103L and
1103R execute the predetermined operation once) is counted for each
sensor 1122. The constant time is not limited to the time needed
when the arms 1103L and 1103R execute the predetermined operation
once. For example, the constant time may be time that is set
through the input device. By determining whether the number of
times of excess N counted for each sensor 1122 exceeds the
predetermined number of times of determination Nj, for each sensor
1122, the comparing/determining unit 1164 determines whether there
is abnormality in the actuators Ac1002 to Ac1015 of the arms 1103L
and 1103R. The comparing/determining unit 1164 will be described in
detail below.
[0111] The zero point adjusting unit 1165 outputs a reset signal to
each sensor 1122 and adjusts a zero point of each sensor 1122,
whenever the arms 1103L and 1103R execute the predetermined
operation corresponding to the recording section set by the section
setting unit 1162, to suppress the change in the ambient
temperature due to heat generation of the actuators Ac1002 to
Ac1015 of the arms 1103L and 1103R or an influence of the
temperature drift of each sensor 1122 generated by self heat
generation.
[0112] FIG. 5 is a diagram illustrating the detailed configuration
of the sensor units 1120L and 1120R, the high-pass filter unit
1161, and the comparing/determining unit 1164 according to the
first embodiment. In FIG. 5, the normative waveform recording unit
1163 and the output waveform recording unit 1167 are not
illustrated.
[0113] In FIG. 5, as described above, each of the sensor units
1120L and 1120R includes the sensor fixing jig 1121 that is
provided on the inner side of the casing of the trunk portion 1102
and is formed in an annular shape and the three sensors 1122 that
are provided in the sensor fixing jig 1121 and have an
approximately rectangular solid shape. The sensor fixing jig 1121
of each of the sensor units 1120L and 1120R has an opening 1121A
where the wiring line of the actuators Ac1002 to Ac1015 provided in
the arms 1103L and 1103R can be inserted, at the approximately
central portion. The three sensors 1122 of the sensor unit 1120L
are disposed on an inner surface of the sensor fixing jig 1121,
that is, a surface (the surface on the left side in FIG. 2 and the
surface in front of a plane of paper in FIG. 5) not attached to the
base of the stator of the actuator Ac1002, such that the three
sensors 1122 are radially disposed at an equal interval on the same
circumference. The three sensors 1122 of the sensor unit 1120R are
disposed on the inner surface of the sensor fixing jig 1121, that
is, a surface (the surface on the right side in FIG. 2 and the
surface in front of a plane of paper in FIG. 5) not attached to the
base of the stator of the actuator Ac1009, such that the three
sensors 1122 are radially disposed at an equal interval on the same
circumference.
[0114] In this embodiment, a force sensor that has a piezoelectric
body made of a material having a natural frequency (rigidity)
higher than that of the metallic material to be the structural
material forming each portion of the arms 1103L and 1103R, in this
example, a sensor where quartz is used as the piezoelectric body is
used as each sensor 1122. This is because that the change force
including a high frequency component can be detected when a natural
frequency of the force sensor is high and the quartz has a natural
frequency (or rigidity) higher than that of the metallic material
that is the structural material forming each portion of the arms
1103L and 1103R. Therefore, a minute high frequency vibration (fast
deformation and dynamic strain) that is transmitted to the
structural material of each portion of the arms 1103L and 1103R can
be detected.
[0115] Each sensor 1122 is not limited to the sensor where the
quartz is used as the piezoelectric body and may be a force sensor
that has a piezoelectric body made of a material having a natural
frequency higher than that of the structural material forming each
portion of the arms 1103L and 1103R. In this case, one sensor 1122
detects strain of one direction that is generated in the sensor
fixing jig 1121. Meanwhile, an abnormal vibration or impact based
on abnormality of the rotation member such as the actuators Ac1002
to Ac1015 of the arms 1103L and 1103R or the decelerator is
transmitted to the sensor fixing jig 1121 through the structural
material of each portion of the arms 1103L and 1103R in plural
directions. Therefore, by providing the three sensors 1122 in each
sensor fixing jig 1121 as described above, strain of three
directions that is generated in each sensor fixing jig 1121 can be
detected. Each sensor 1122 of the sensor unit 1120L detects the
amount of strain of a radial direction of the sensor fixing jig
1121 due to the force applied to the arm 1103L as a voltage and
each sensor 1122 of the sensor unit 1120R detects the amount of
strain of a radial direction of the sensor fixing jig 1121 due to
the force applied to the arm 1103R as a voltage. The voltage that
is obtained by each sensor 1122 is amplified by the amplifying unit
1123 and is input to each high-pass filter 1161A (to be described
below) of the high-pass filter unit 1161.
[0116] The high-pass filter unit 1161 has plural high-pass filters
1161A (or band-pass filters using a high frequency band as a
pass-band) that can extract a high frequency vibration component of
the output signal of the sensor 1122, and the high frequency
component of the output signal of each sensor 1122 that is
amplified by the amplifying unit 1123 is extracted by each
high-pass filter 1161A. In each high-pass filter 1161A, a cut-off
frequency is determined such that a frequency component other than
a frequency due to abnormality of the arms 1103L and 1103R
(frequency component due to an event other than a contact such as
an operation of the actuators Ac1002 to Ac1015) can be removed.
[0117] By determining whether the number of times of excess N
counted for each sensor 1122 exceeds the number of times of
determination Nj for each sensor 1122 as described above, the
comparing/determining unit 1164 determines whether there is
abnormality in the actuators Ac1002 to Ac1015 of the arms 1103L and
1103R. Specifically, when the number of times of excess N for all
of the sensors 1122 is within the number of times of determination
Nj, the comparing/determining unit 1164 determines that there is no
abnormality in the actuators Ac1002 to Ac1015. When the number of
times of excess N for one sensor 1122 among all of the sensors 1122
exceeds the number of times of determination Nj, the
comparing/determining unit 1164 determines that there is
abnormality in the actuators Ac1002 to Ac1015.
[0118] The comparing/determining unit 1164 executes the above
determination while changing the number of times of determination
Nj according to the operation speed of the arms 1103L and 1103R.
That is, in the case where abnormality based on aging is generated
in the rotation member such as the actuators Ac 1002 to Ac1015 of
the arms 1103L and 1103R or the decelerator and a cyclic abnormal
vibration or impact is generated at the time of the operation of
the arms 1103L and 1103R, when the operation speed of the arms
1103L and 1103R is fast, the number of times of generating the
cyclic abnormal vibration increases, and when the operation speed
is slow, the number of times of generating the cyclic abnormal
vibration decreases. For this reason, when the number of times of
determination Nj is set to a constant value, erroneous detection of
the abnormality is caused depending on the operation speed.
Therefore, in this embodiment, the comparing/determining unit 1164
executes the above determination while changing the number of times
of determination Nj according to the operation speed of the arms
1103L and 1103R, and prevents the erroneous detection.
[0119] FIGS. 6A and 6B are diagrams illustrating a predetermined
operation that is executed by the arms 1103L and 1103R according to
the first embodiment in a state in which there is no abnormality
and an output value V of the sensor 1122 during the predetermined
operation.
[0120] FIG. 6A schematically illustrates an example of the
predetermined operation that is executed by the arms 1103L and
1103R in a state in which there is no abnormality. In the example
illustrated in FIG. 6A, in a state in which there is no abnormality
in the arms 1103L and 1103R at the time of instructing and in an
environment in which the product P that is an object to be gripped
does not exist and there is no obstacle around the robot 1100
(within the movable range of the arms 1103L and 1103R), that is, in
a state in which an object does not contact the arms 1103L and
1103R, a predetermined operation according to the position
instruction from the robot controller 1150, that is, an operation
from the instructed operation start position (position illustrated
at the left side of FIG. 6A) to the instructed operation completion
position (position illustrated at the right side of FIG. 6A) is
executed. The operation completion position is set to the position
where the hands 1111L and 1111R can grip the minimum product P of
the products P conveyed by the belt conveyor 1002.
[0121] FIG. 6B illustrates an example of the normative waveform
that is recorded in the normative waveform recording unit 1163 to
correspond to the operation illustrated in FIG. 6A, in which a
horizontal axis indicates time t and a vertical axis indicates an
output value V of the sensor 1122. In the example illustrated in
FIG. 6B, in the normative waveform recording unit 1163, the time
history of the output value V of the sensor 1122 while the
operation corresponding to the recording section described above
and illustrated in FIG. 6A is executed once in a state in which
there is no abnormality in the arms 1103L and 1103R is recorded as
the normative waveform. The normative waveform can always be
recorded, when there is no abnormality in the arms 1103L and 1103R.
In this embodiment, an example of the case where the normative
waveform is recorded at the time of instructing the predetermined
operation with respect to the robot 1100 will be described.
[0122] FIGS. 7A and 7B are diagrams illustrating a predetermined
operation that is executed by the arms 1103L and 1103R according to
the first embodiment at the time of activating and an output value
V of the sensor 1122 during the predetermined operation.
[0123] FIG. 7A schematically illustrates an example of the
predetermined operation that is executed by the arms 1103L and
1103R at the time of activating. In the example illustrated in FIG.
7A, when the product P to be a grip object does not exist in a
movable range at the time of activating (for example, immediately
after starting conveyance of the product P or at the time of
stopping the conveyance and performing checking), in a state in
which abnormality based on aging is generated in the rotation
member such as the actuators Ac 1002 to Ac1015 of the arms 1103L
and 1103R or the decelerator, the arms 1103L and 1103R execute a
predetermined operation according to the position instruction from
the robot controller 1150, that is, an operation from the
instructed operation start position (position illustrated at the
left side of FIG. 7A) to the instructed operation completion
position (position illustrated at the right side of FIG. 7A). In
the example that is illustrated in FIG. 7A, the case where the arms
1103L and 1103R execute the predetermined operation when the
product P that is the grip object does not exist in the movable
range as described above is illustrated. Therefore, similar to the
case of FIG. 6A, the operation to the operation completion position
is executed without gripping the product P by the hands 1111L and
1111R. Although not illustrated in the drawings, when the product P
to be the grip object exists, the arms 1103L and 1103R is operated
from the operation start position to the inner side more than both
sides of the product P on the belt conveyor 1002. If the product P
contacts the arms 1103L and 1103R, the arms 1103L and 1103R stop
the operation at the corresponding position such that the product P
is gripped by the hands 1111L and 1111R.
[0124] FIG. 7B illustrates an example of the normative waveform
that is recorded in the output waveform recording unit 1167 to
correspond to the operation illustrated in FIG. 7A, in which a
horizontal axis indicates time t and a vertical axis indicates an
output value V of the sensor 1122. In the example illustrated in
FIG. 7B, in the output waveform recording unit 1167, the time
history of the output value V of the sensor 1122 while the arms
1103L and 1103R execute the operation illustrated in FIG. 7A once
in a state in which abnormality based on aging is generated in the
rotation member such as the actuators Ac1002 to Ac1015 or the
decelerator is recorded as an output waveform. In this example,
when abnormality based on aging is generated in the rotation member
such as the actuators Ac1002 to Ac1015 of the arms 1103L and 1103R
or the decelerator, an abnormal place cyclically appears in a
rotation phase. For this reason, when the arms 1103L and 1103R are
operated, a abnormal vibration or impact is easily generated. In
general, when the cyclic abnormal vibration or impact is generated
in the arms 1103L and 1103R, the impact force due to the abnormal
vibration or impact is transmitted to the arms 1103L and 1103R, and
the output value V of the sensor 1122 increases as compared with
the case where the abnormal vibration or impact is not generated.
Therefore, when abnormality based on aging is generated in the
rotation member such as the actuators Ac1002 to Ac1015 or the
decelerator, a section where the output value V of the sensor 1122
increases cyclically exists in the output waveform. In the output
waveform that is illustrated in FIG. 7B, sections of four places
where the output value V of the sensor 1122 increases exist.
[0125] FIGS. 8A and 8B are diagrams illustrating an example of a
method of detecting whether there is abnormality in the arms 1103L
and 1103R according to the first embodiment. FIG. 8A illustrates
the normative waveform corresponding to FIG. 6B and the output
waveform corresponding to FIG. 7B, in which a horizontal axis
indicates time t and a vertical axis indicates an output value V of
the sensor 1122. FIG. 8B illustrates a waveform of a time-series
change of the difference "D", in which a horizontal axis indicates
time t and a vertical axis indicates the difference "D".
[0126] In FIGS. 8A and 8B, as described above, when there is
abnormality in the arms 1103L and 1103R, a section where the output
value V of the sensor 1122 increases cyclically exists in the
output waveform. Therefore, by comparing the two waveforms of the
normative waveform at the time of instructing recorded in the
normative waveform recording unit 1163 and the output waveform at
the time of activating recorded in the output waveform recording
unit 1167 in a state where there is no abnormality in the arms
1103L and 1103R, the cyclic change of the output waveform with
respect to the normative waveform can be detected. Therefore, it
can be detected whether there is abnormality in the actuators
Ac1002 to Ac1015 of the arms 1103L and 1103R. That is, by
determining whether the number of times of excess N where the
difference "D" of the normative waveform and the output waveform
exceeding the threshold value Dth when the arms 1103L and 1103R
execute the predetermined operation once exceeds the number of
times of determination Nj according to the operation speed of the
arms 1103L and 1103R, it can be determined whether there is
abnormality in the actuators Ac1002 to Ac1015. Specifically, when
the number of times of excess N is within the number of times of
determination Nj, it can be determined that there is no abnormality
in the actuators Ac1002 to Ac1015. When the number of times of
excess N exceeds the number of times of determination Nj, it can be
determined that there is abnormality in the actuators Ac1002 to
Ac1015. In the examples that are illustrated in FIGS. 8A and 8B,
the number of times of excess N is "4" as illustrated in FIG. 8B.
Therefore, when the number of times of determination Nj is "3" or
less, it is determined that there is abnormality in the actuators
Ac1002 to Ac1015.
[0127] FIG. 9 is a flowchart illustrating a control sequence that
is executed by the robot controller 1150 according to the first
embodiment.
[0128] In FIG. 9, a process that is illustrated in a flow is
started when a predetermined operation start manipulation is
executed through the input device. First, in step S1010, the robot
controller 1150 determines whether an operation mode of the robot
1100 is an "instruction mode" to perform instructing or an
"activation mode" to perform activating, on the basis of input
information input through the input device. When the operation mode
of the robot 1100 is the "instruction mode", the determination
result of step S1010 is satisfied and the process proceeds to step
S1020.
[0129] In step S1020, the robot controller 1150 sets the recording
section in the section setting unit 1162, on the basis of the input
information input through the input device.
[0130] Then, in step S1030, the robot controller 1150 outputs the
reset signal to each sensor 1122 and adjusts a zero point of each
sensor 1122, in the zero point adjusting unit 1165.
[0131] Then, the process proceeds to step S1040 and the robot
controller 1150 outputs a position instruction with respect to each
of the actuators Ac1001 to Ac1015 calculated in the operation
instructing unit 1151 on the basis of the instruction information
(information indicating the operation start position and the
operation completion position) with respect to each of the arms
1103L and 1103R instructed through the input device, to each of the
actuators Ac1001 to Ac1015, and starts the predetermined operation
(refer to FIG. 6A) according to the position instruction in the
arms 1103L and 1103R, in a state in which there is no abnormality
in the arms 1103L and 1103R and an object does not contact the arms
1103L and 1103R.
[0132] Then, in step S1050, the robot controller 1150 starts
recording of the normative waveform for each sensor 1122, in the
normative waveform recording unit 1163. Therefore, while the arms
1103L and 1103R executes the predetermined operation corresponding
to the recording section set in step S1020 and started in step
S1040 in a state in which there is no abnormality in the arms 1103L
and 1103R and an object does not contact the arms 1103L and 1103R,
the normative waveform recording unit 1163 records the time history
of the output value V of each sensor 1122 based on the high
frequency vibration component amplified by the amplifying unit 1123
and extracted by each high-pass filter 1161A as the normative
waveform for each sensor 1122.
[0133] If the arms 1103L and 1103R are operated until the operation
completion position, the process proceeds to step S1060 and the
robot controller 1150 completes the operation in the arms 1103L and
1103R.
[0134] Then, in step S1070, the robot controller 1150 completes
recording of the normative waveform for each sensor 1122, in the
normative waveform recording unit 1163. The robot controller 1150
ends the process that is illustrated in the flow. The process that
is illustrated in the flow is executed by the robot controller
1150, whenever the predetermined operation start manipulation is
executed through the input device.
[0135] Meanwhile, in step S1010, when the operation mode of the
robot 1100 is the "activation mode", the determination result of
step S1010 is not satisfied and the process proceeds to step
S1080.
[0136] In step S1080, the robot controller 1150 sets the threshold
value Dth in the threshold value setting unit 1166, on the basis of
the input information input through the input device.
[0137] Then, the process proceeds to step S1090 and the robot
controller 1150 adjusts a zero point of each sensor 1122 in the
zero point setting unit 1165, similar to step S1030.
[0138] Then, in step S1100, the robot controller 1150 outputs a
position instruction with respect to each of the actuators Ac1001
to Ac1015 calculated in the operation instructing unit 1151 on the
basis of the instruction information (information indicating the
operation start position and the operation completion position)
with respect to each of the arms 1103L and 1103R instructed through
the input device, to each of the actuators Ac1001 to Ac1015, and
starts the predetermined operation (refer to FIG. 7A) according to
the position instruction in the arms 1103L and 1103R, when the
product P to be the grip object does not exist within the movable
range of the arms 1103L and 1103R.
[0139] Then, the process proceeds to step S1110 and the robot
controller 1150 starts recording of the output waveform for each
sensor 1122, in the output waveform recording unit 1167. Therefore,
when the product P to be the grip object does not exist within the
movable range of the arms 1103L and 1103R, while the predetermined
operation started in step S1040 is executed by the arms 1103L and
1103R, the output waveform recording unit 1167 records the time
history of the output value V of each sensor 1122 based on the high
frequency vibration component amplified by the amplifying unit 1123
and extracted by each high-pass filter 1161A as the output waveform
for each sensor 1122.
[0140] Then, if the arms 1103L and 1103R are operated until the
operation completion position, the process proceeds to step S1120
and the robot controller 1150 completes the operations in the arms
1103L and 1103R.
[0141] Then, the process proceeds to step S1130 and the robot
controller 1150 completes recording of the output waveform for each
sensor 1122, in the output waveform recording unit 1167.
[0142] Then, in step S1140, the robot controller 1150 compares the
normative waveform recorded in the normative waveform recording
unit 1163 for each sensor 1122 and the output waveform recorded in
the output waveform recording unit 1167 for each sensor 1122, for
each sensor 1122 in the comparing/determining unit 1164, and
calculates the difference "D" for each sensor 1122. The robot
controller 1150 counts the number of times of excess N where the
difference "D" calculated for each sensor 1122 exceeds the
threshold value Dth set in step S1080 when the arms 1103L and 1103R
execute the predetermined operation started in step S1100 and
completed in step S1120 once, for each sensor 1122. By determining
whether the number of times of excess N counted for each sensor
1122 exceeds the number of times of determination Nj set according
to the operation speed of the arms 1103L and 1103R for each sensor
1122, it is determined whether there is abnormality in the
actuators Ac1002 to Ac1015 of the arms 1103L and 1103R.
Specifically, when the number of times of excess N for all of the
sensors 1122 is within the number of times of determination Nj, it
is determined that there is no abnormality in the actuators Ac1002
to Ac1015 of the arms 1103L and 1103R. When the number of times of
excess N for one sensor 1122 among all of the sensors 1122 exceeds
the number of times of determination Nj, it is determined that
there is abnormality in the actuators Ac1002 to Ac1015.
[0143] Then, the process proceeds to step S1150 and the robot
controller 1150 determines whether it is determined in step S1140
that there is abnormality in the actuators Ac1002 to Ac1015. When
it is determined that there is no abnormality in the actuators
Ac1002 to Ac1015, the determination result of step S1150 is not
satisfied and the process that is illustrated in the flow ends.
Meanwhile, when it is determined that there is abnormality in the
actuators Ac1002 to Ac1015, the determination result of step S1150
is satisfied and the process proceeds to step S1160.
[0144] In step S1160, the robot controller 1150 intercepts the
output of the position instruction from the operation instructing
unit 1151 to the smoothing processing unit 1153 in the position
instruction intercepting unit 1152, outputs the torque instruction
Tref generated by the servo unit 1154 to each of the actuators
Ac1001 to Ac1015, stops the operation instructed to the arms 1103L
and 1103R, and notifies an external device of the abnormality of
the arms 1103L and 1103R in a notifying unit (not illustrated in
the drawings).
[0145] As described above, the robot 1100 according to this
embodiment has the arms 1103L and 1103R, and in each of the sensor
fixing jigs 1121 that are provided in the bases of the actuators
Ac1002 and Ac1009 of the arms 1103L and 1103R closest to the side
of the base end, the sensors 1122 (in the above example, three
sensors) that have a piezoelectric body having a natural frequency
higher than that of the structure material (metallic material such
as iron or aluminum in the above example) forming each portion of
the arms 1103L and 1103R are provided. By configuring the sensor
1122 as the sensor the piezoelectric body having a natural
frequency higher than that of the structure material forming each
portion of the arms 1103L and 1103R, the following effect can be
obtained. That is, when abnormality based on aging is generated in
the rotation member such as the actuators Ac1002 to Ac1015 of the
arms 1103L and 1103R or the decelerator, the cyclic abnormal
vibration or impact may be generated during the operation of the
arms 1103L and 1103R. Therefore, by providing the sensors 1122
having the piezoelectric body having a natural frequency higher
than that of the structure material forming each portion of the
arms 1103L and 1103R, the high frequency abnormal vibration or the
impact that is generated in the structure material of each portion
of the arms 1103L and 1103R due to the abnormality can be detected,
and it can be detected whether there is abnormality in the
actuators Ac1002 to Ac1015 of the arms 1103L and 1103R. As a
result, functionality of the robot 1100 can be improved.
[0146] Since the sensors 1122 are provided in the bases of the
actuators Ac1002 and Ac1009 of the arms 1103L and 1103R closest to
the side of the base end, the abnormal vibration based on the
rotation member such as all of the actuators Ac1002 to Ac1015 at
the side of the front end or the decelerator can be detected. That
is, abnormality with respect to the entire arms 1103L and 1103R can
be detected.
[0147] In this embodiment, the sensor fixing jig 1121 is provided
on the inner side of the casing of the trunk portion 1102. Thereby,
since each sensor 1122 can be provided in the casing, each sensor
1122 can be prevented from being destroyed due to the contact or
collision of the object from the outside of the casing. Further,
the sensor 1122 can be protected from a droplet or dust from the
outside of the casing.
[0148] In this embodiment, particularly, the three sensors 1122 are
provided in the sensor fixing jig 1121. The three sensors 1122 are
radially disposed at an equal interval on the same circumference.
By providing the three sensors 1122, the strain of the three
directions that is generated in the sensor fixing jig 1121 can be
detected and the abnormal vibration or the impact can be detected
with high precision. By radially disposing the three sensors 1122
at an equal interval on the same circumference, detection
sensitivity of the sensors 1122 can be approximately equalized in a
circumferential direction without deviating the detection
sensitivity in one direction. Therefore, the abnormal vibration or
the impact that is transmitted to the sensor fixing jig 1121 from
the plural directions through the structural material of each
portion of the arms 1103L and 1103R can be detected with high
precision.
[0149] In this embodiment, in particular, the sensor fixing jig
1121 is formed in an annular shape with the opening 1121A at the
approximately central portion. By forming the sensor fixing jig
1121 positioned at the side of the base end of each of the arms
1103L and 1103R in the annular shape with the opening 1121A at the
approximately central portion, the wiring line of the actuators
Ac1002 to Ac1015 of the arms 1103L and 1103R can be inserted into
the opening 1121A of the sensor fixing jig 1121 and can be drawn
(around the side of the trunk portion 1102). Thereby, since the
wiring line can be drawn without being exposed to the outside of
the casing, the wiring line can be protected and an exterior
appearance of the robot 1100 can be improved.
[0150] In this embodiment, particularly, each sensor 1122 is the
sensor where the quartz is used as the piezoelectric body. Thereby,
the high frequency abnormal vibration or the impact that is
generated in the structural material of each portion of the arms
1103L and 1103R due to the abnormality based on aging of the
rotation member such as the actuators Ac1002 and Ac1015 of the arms
1103L and 1103R or the decelerator can be securely detected, and it
can be detected with high precision whether there is abnormality in
the actuators Ac1002 and Ac1015 of the arms 1103L and 1103R.
[0151] The first embodiment has been described. However, the
embodiment may be implemented by various different embodiments
other than the first embodiment. Therefore, the various different
embodiments are hereinafter described as modifications.
[0152] (1) Case where the Robot is Applied to Detection of a
Contact of an Object
[0153] In the above embodiment, the robot disclosed in the present
application is applied to the detection of the abnormality of the
arms 1103L and 1103R. However, the embodiment is not limited
thereto and the robot disclosed in the present application may be
applied to detection of a contact of the object with respect to the
arms 1103L and 1103R.
[0154] In this modification, a contact detecting unit (not
illustrated in the drawings) of the robot controller 1150 detects
whether the object contacts the arms 1103L and 1103R, on the basis
of the output value V (output signal) of each sensor 1122 of the
sensor units 1120L and 1120R. In this specification, the object is
defined as a meaning including the product P gripped by the robot
1100, the robot 1100, a work apparatus such as the belt conveyor
1002, a part of a building such as a wall, and an organism such as
a living body.
[0155] As described above, each sensor 1122 of the sensor units
1120L and 1120R detects the force that is applied to the arms 1103L
and 1103R. As the force that is applied to the arms 1103L and
1103R, the internal force that is generated by the operation of the
arms 1103L and 1103R and the external force that is applied to the
arms 1103L and 1103R from the outside are considered. The external
force is not applied to the arms 1103L and 1103R when the arms
1103L and 1103R are operated in a state in which the object
illustrated in FIG. 6A does not contact the arms 1103L and 1103R.
Therefore, each sensor 1122 detects only the vibration due to the
internal force. Meanwhile, when the object contacts the arms 1103L
and 1103R, the internal force and the external force are applied to
the arms 1103L and 1103R. Therefore, each sensor 1122 detects the
vibrations due to the internal force and the external force. For
this reason, when the object contacts the arms 1103L and 1103R, the
output value V of the sensor 1122 increases by the amount
corresponding to the external force. Therefore, in this
modification, the contact detecting unit compares the output value
V of the sensor 1122 when the arms 1103L and 1103R execute the
predetermined operation at the time of activating with the
normative waveform previously recorded as the output value V of the
sensor 1122 when the arms 1103L and 1103R execute the predetermined
operation in a state in which the object does not contact the arms
1103L and 1103R, and determines whether the object contacts the
arms 1103L and 1103R.
[0156] FIG. 10 schematically illustrates an example of the
predetermined operation that is executed by the arms 1103L and
1103R at the time of activating. In the example that is illustrated
in FIG. 10, at the time of activating, under an environment in
which an obstacle B exists around the robot 1100 (within the
movable range of the arms 1103L and 1103R), the arms 1103L and
1103R execute the predetermined operation according to the position
instruction from the robot controller 1150, that is, the operation
from the instructed operation start position (position illustrated
at the left side of FIG. 10) to the instructed operation completion
position. At this time, the contact detecting unit determines
whether the object contacts the arms 1103L and 1103R, using the
above method. The arms 1103L and 1103R are operated from the
operation start position to the inner side more than both sides of
the product P on the belt conveyor 1002 (not illustrated in FIG.
10). When the contact detecting unit detects the contact of the
object (obstacle B in this example) with respect to the arms 1103L
and 1103R while the arms 1103L and 1103R execute the operation
until the operation completion position, the robot controller 1150
stops the operation of the arms 1103L and 1103R at the
corresponding position (position illustrated at the right side of
FIG. 10).
[0157] In this example, the case where the control operation is
performed such that the contact of the obstacle B with respect to
the arms 1103L and 1103R is detected and the operation is stopped
when the contact is detected is described. However, the embodiment
is not limited thereto and the control operation may be performed
such that the contact of the product P with respect to the arms
1103L and 1103R is detected, the operation is stopped when the
contact is detected, and the product P is gripped by the hands
1111L and 1111R.
[0158] Even in this modification, the same effect as that of the
above embodiment can be obtained. Since the external force applied
to the arms 1103L and 1103R can be detected by the sensor 1122, it
can be detected whether the object contacts the arms 1103L and
1103R. As described above, since the sensors 1122 are provided in
the bases of the actuators Ac1002 and Ac1009 of the arms 1103L and
1103R closest to the side of the base end, a contact at the side of
the front end can be detected. That is, a contact with respect to
the entire arms 1103L and 1103R can be detected. Therefore, an
excessive load can be avoided from being generated with respect to
the robot 1100 or the object existing around the robot 1100.
[0159] (2) Case where the Robot is Applied to a Single-Arm
Robot
[0160] In the above embodiment, the robot disclosed in the present
application is applied to the robot 1100 to be the dual-arm robot
that has the two arms 1103L and 1103R. However, the embodiment is
not limited thereto and the robot disclosed in the present
application may be applied to a single-arm robot that has one robot
arm. Even in this case, the same effect as that of the above
embodiment or the modification of (1) can be obtained.
[0161] In addition to the configuration described above, the
configuration where the methods according to the embodiment and the
modifications are appropriately combined may be used.
[0162] Although not specifically described, this embodiment can be
variously changed in a range that does not depart from the sprit
and scope of the embodiment.
[0163] Next, a second embodiment will be described.
[0164] In a field of robots, it is preferable to avoid an excessive
load from being generated with respect to a robot or an object
existing around the robot. For this reason, various technologies
for detecting generation or non-generation of a contact (external
force) with respect to the robot are studied.
[0165] For example, a technology for attaching a force detector to
detect the external force to a base end of a robot arm and stopping
an operation of the robot arm on the basis of the detection result
of the force detector or operating the robot arm in a reduction
direction of the external force when the excessive external force
is applied is disclosed in Japanese Patent Application Laid-Open
(JP-A) No. 2006-21287.
[0166] A sensory inspection to evaluate a quality by human five
senses and bodily sensation is used in various fields. In a
manufacturing/assembling process of various mechanical products or
electronic apparatuses, when it is inspected whether the mechanical
products or the electronic apparatuses are in a normal state or an
abnormal state (it is inspected whether there is abnormality), a
sensory inspection based on a tactile sense is generally used.
[0167] However, since a human sensory organ is used as a measuring
instrument in the sensory inspection, the inspection result is
affected by a skill or a physical condition of an inspector.
Therefore, it is preferable to develop a robot that can inspect
inspected object such as the mechanical product or the electronic
apparatus with high precision without depending on the sensor
inspection.
[0168] When the inspected object is inspected by the robot, it is
needed to detect the change of the minute force or the vibration
that is generated in the front end of the robot arm. However, in
the configuration according to the related art in which the force
detector is provided in the robot, an inspection with high
precision is not possible.
[0169] According to one aspect of an embodiment, a robot that can
detect with high precision whether the robot and the inspected
object are in a normal state or an abnormal state is provided.
[0170] According to the robot in this embodiment, it can be
detected with high precision whether the robot and the inspected
object are in a normal state or an abnormal state.
[0171] Hereinafter, this embodiment will be described with
reference to the drawings. This embodiment is an example of the
case where the robot disclosed in the present application is
applied to detection of abnormality of the inspected object to be
the mechanical product.
[0172] FIG. 11 is a conceptual diagram illustrating the entire
configuration of a robot system that includes the robot according
to the second embodiment. FIG. 12 is a top view illustrating the
configuration of the robot according to the second embodiment.
[0173] In FIGS. 11 and 12, a robot system 2001 according to this
embodiment is a system that detects whether the inspected object to
be the mechanical product is normal (described below) or abnormal
(described below). The robot system 2001 includes a robot 2100 and
a robot controller 2150 that controls the robot 2100. The robot
2100 is a dual-arm robot and has a base 2101, a trunk portion 2102,
two arms 2103L and 2103R (robot arms), and a sensor 2130 (first
strain sensor), and an A/D converter 2131.
[0174] The base 2101 is fixed to a mounting surface (floor) by an
anchor bolt (not illustrated in the drawings). The trunk portion
2102 has a joint portion in which an actuator Ac2001 driven to
rotate around a rotation axis Ax2001 is provided. The trunk portion
2102 is disposed to rotate with respect to the base 2101 through
the first joint portion and rotates in a direction approximately
horizontal to the mounting surface by driving of the actuator
Ac2001 provided in the first joint portion. The trunk portion 2102
supports the arms 2103L and 2103R that are configured as separate
objects, at one side (right side in FIGS. 11 and 12) and the other
side (left side in FIGS. 11 and 12), respectively.
[0175] The arm 2103L is a manipulator that is provided on one side
of the trunk portion 2102. The arm 2103L has a shoulder portion
2104L, an upper arm A portion 2105L, an upper arm B portion 2106L,
a lower arm portion 2107L, a wrist A portion 2108L, a wrist B
portion 2109L, a flange 2110L, a hand 2111L, and second to eighth
joint portions in which actuators Ac2002 to Ac2008 configured to
rotate the individual portions are provided, respectively.
[0176] The shoulder portion 2104L is connected to the trunk portion
2102 to rotate through the second joint portion and rotates around
a rotation axis Ax2002 approximately horizontal to the mounting
surface by driving of the actuator Ac2002 provided in the second
joint portion. The upper arm A portion 2105L is connected to the
shoulder portion 2104L to rotate through the third joint portion
and rotates around a rotation axis Ax2003 orthogonal to the
rotation axis Ax2002 by driving of the actuator Ac2003 provided in
the third joint portion. The upper arm B portion 2106L is connected
to a front end of the upper arm A portion 2105L shoulder portion
2104L to rotate through the fourth joint portion and rotates around
a rotation axis Ax2004 orthogonal to the rotation axis Ax2003 by
driving of the actuator Ac2004 provided in the fourth joint
portion. The lower arm portion 2107L is connected to the upper arm
B portion 2106L to rotate through the fifth joint portion and
rotates around a rotation axis Ax2005 orthogonal to the rotation
axis Ax2004 by driving of the actuator Ac2005 provided in the fifth
joint portion. The wrist A portion 2108L is connected to a front
end of the lower arm portion 2107L to rotate through the sixth
joint portion and rotates around a rotation axis Ax2006 orthogonal
to the rotation axis Ax2005 by driving of the actuator Ac2006
provided in the sixth joint portion. The wrist B portion 2109L is
connected to the wrist A portion 2108L to rotate through the
seventh joint portion and rotates around a rotation axis Ax2007
orthogonal to the rotation axis Ax2006 by driving of the actuator
Ac2007 provided in the seventh joint portion. The flange 2110L is
connected to a front end of the wrist B portion 2109L to rotate
through the eighth joint portion and rotates around a rotation axis
Ax2008 orthogonal to the rotation axis Ax2007 by driving of the
actuator Ac2008 provided in the eighth joint portion. The hand
2111L is attached to a front end of the flange 2110L and rotates
according to the rotation of the flange 2110L.
[0177] The arm 2103R is a manipulator that is provided on the other
side of the trunk portion 2102. Similar to the arm 2103L, the arm
2103R has a shoulder portion 2104R, an upper arm A portion 2105R,
an upper arm B portion 2106R, a lower arm portion 2107R, a wrist A
portion 2108R, a wrist B portion 2109R, a flange 2110R, a hand
2107R, and ninth to fifteenth joint portions in which actuators
Ac2009 to Ac2015 to drive rotation of the individual portions are
provided, respectively.
[0178] The shoulder portion 2104R is connected to the trunk portion
2102 to rotate through the ninth joint portion and rotates around a
rotation axis Ax2009 approximately horizontal to the mounting
surface by driving of the actuator Ac2009 provided in the ninth
joint portion. The upper arm A portion 2105R is connected to the
shoulder portion 2104R to rotate through the tenth joint portion
and rotates around a rotation axis Ax2010 orthogonal to the
rotation axis Ax2009 by driving of the actuator Ac2010 provided in
the tenth joint portion. The upper arm B portion 2106R is connected
to a front end of the upper arm A portion 2105R shoulder portion
2104L to rotate through the eleventh joint portion and rotates
around a rotation axis Ax2011 orthogonal to the rotation axis
Ax2010 by driving of the actuator Ac2011 provided in the eleventh
joint portion. The lower arm portion 2107R is connected to the
upper arm B portion 2106R to rotate through the twelfth joint
portion and rotates around a rotation axis Ax2012 orthogonal to the
rotation axis Ax2011 by driving of the actuator Ac2012 provided in
the twelfth joint portion. The wrist A portion 2108R is connected
to a front end of the lower arm portion 2107R to rotate through the
thirteenth joint portion and rotates around a rotation axis Ax2013
orthogonal to the rotation axis Ax2012 by driving of the actuator
Ac2013 provided in the thirteenth joint portion. The wrist B
portion 2109R is connected to the wrist A portion 2108R to rotate
through the fourteenth joint portion and rotates around a rotation
axis Ax2014 orthogonal to the rotation axis Ax2013 by driving of
the actuator Ac2014 provided in the fourteenth joint portion. The
flange 2110R is connected to a front end of the wrist B portion
2109R to rotate through the fifteenth joint portion and rotates
around a rotation axis Ax2015 orthogonal to the rotation axis
Ax2014 by driving of the actuator Ac2015 provided in the fifteenth
joint portion. The hand 2111R is attached to a front end of the
flange 2110R and rotates according to the rotation of the flange
2110R.
[0179] In this example, each of the arms 2103L and 2103R has seven
joint portions, that is, degrees of freedom of 7 (redundant degree
of freedom). However, the degrees of freedom of each of the arms
2103L and 2103R are not limited to "7".
[0180] As structural materials that form the shoulder portions
2104L and 2104R, the upper arm A portion 2105L and 2105R, the upper
arm B portions 2106L and 2106R, the lower arm portions 2107L and
2107R, the wrist A portions 2108L and 2108R, the wrist B portions
2109L and 2109R, the flanges 2110L and 2110R, and the hands 2111L
and 2111R of the arms 2103L and 2103R, metallic materials such as
iron or aluminum are used. The arms 2103L and 2103R are configured
to be thin and light like the front end side (side of the hands
2111L and 2111R), in order to suppress an increase in the operation
torque of the actuators positioned at the side of the base end
(side of the shoulder portions 2104L and 2104R) and secure a
smoothing operation. For this reason, in the vicinity of the front
end of each of the arms 2103L and 2103R, an extra space in the
casing decreases.
[0181] As illustrated in FIG. 12, the trunk portion 2102 is formed
to protrude forward in a horizontal direction from the first joint
portion to the second and ninth joint portions, with respect to the
base 2101, such that the rotation axis Ax2001 of the first joint
portion and the rotation axiss Ax2002 and Ax2009 of the second and
ninth joint portions are offset by the length D1 in a direction
approximately horizontal to the mounting surface. Thereby, a space
of the lower side of the shoulder portions 2104L and 2104R can be
used as a work space, and a reachable range of the arms 2103L and
2103R can be enlarged by rotating the rotation axis Ax2001.
[0182] A shape of the upper arm B portion 2106R is set such that
the positions of the rotation axis Ax2001 of the eleventh joint
portion and the rotation axis Ax2012 of the twelfth joint portion
in plan view are offset by the length D2. A shape of the lower arm
portion 2107R is set such that the positions of the rotation axis
Ax2012 of the twelfth joint portion and the rotation axis Ax2013 of
the thirteenth joint portion in plan view are offset by the length
D3. When the rotation axis Ax2011 and the rotation axis Ax2013
takes an approximately horizontal posture, the offset length of the
rotation axis Ax2011 and the rotation axis Ax2013 becomes (D2+D3).
Thereby, when the twelfth joint portion corresponding to a human
"elbow" is bent, clearance of the upper arm A portion 2105R and the
upper arm B portion 2106R corresponding to a human "upper arm" and
the lower arm portion 2107R corresponding to a human "lower arm"
can be greatly secured. Even when the hand 2111R comes close to the
trunk portion 2102, a freedom degree of the arm 2103R at the time
of an operation increases.
[0183] Although not clearly illustrated in FIG. 12, similar to the
arm 2103R, in the arm 2103L, a shape of the upper arm B portion
2106L is set such that the positions of the rotation axis Ax2004 of
the fourth joint portion and the rotation axis Ax2005 of the fifth
joint portion in upper view are offset by the length D2. A shape of
the lower arm portion 2107L is set such that the positions of the
rotation axis Ax2005 of the fifth joint portion and the rotation
axis Ax2006 of the sixth joint portion in upper view are offset by
the length D3. When the rotation axis Ax2004 and the rotation axis
Ax2006 takes an approximately horizontal posture, the offset length
of the rotation axis Ax2004 and the rotation axis Ax2006 becomes
(D2+D3).
[0184] One sensor 2130 is provided in the vicinity of the front end
of the casing of each of the arms 2103L and 2103R, in this example,
on an external surface of the casing of each of the wrist B
portions 2109L and 2109R. In this embodiment, as each sensor 2130,
a force sensor that has a piezoelectric body made of a material
having a natural frequency (or rigidity) higher than that of the
metallic material to be the structural material forming each
portion of the arms 2103L and 2103R, in this example, a sensor
where the quartz is used as the piezoelectric body is used. This is
because that the change force including a higher frequency
component can be detected as the force sensor has a higher natural
frequency and the quartz has a natural frequency (or rigidity)
higher than that of the metallic material to be the structural
material forming each portion of the arms 2103L and 2103R.
Therefore, a minute high frequency vibration (fast deformation and
dynamic strain) that is transmitted to the front ends (hands 2111L
and 2111R) of the arms 2103L and 2103R can be detected. The sensor
2130 that is provided on the external surface of the casing of the
wrist B portion 2109L detects the force (in detail, amount of
strain caused by a vibration due to the impact force applied to the
front end side more than the wrist B portion 2109L, not the
magnitude of the force) applied to the front end side (hand 2111L)
more than the wrist B portion 2109L of the arm 2103L as a voltage.
The sensor 2130 that is provided on the external surface of the
casing of the wrist B portion 2109R detects the force (in detail,
amount of strain caused by a vibration due to the impact force
applied to the front end side more than the wrist B portion 2109L,
not the magnitude of the force) applied to the front end side (hand
2111R) more than the wrist B portion 2109R of the arm 2103R as a
voltage. The voltage that is obtained by each sensor 2130 is input
to the high-pass filter unit 2161 (refer to FIG. 15 to be described
below) of the robot controller 2150 through an amplifying unit 2132
(refer to FIG. 15 to be described below) and the A/D converter
2131.
[0185] In this example, one sensor 2130 is provided on the external
surface of the casing of each of the wrist B portions 2109L and
2109R. However, the embodiment is not limited thereto and the
sensor 2130 may be provided at the different position (for example,
on the external surface of the casing of each of the hands 2111L
and 2111R or in the casing of each of the wrist B portions 2109L
and 2109R) in the vicinity of the front end of the casing of each
of the arms 2103L and 2103R. In this example, the sensor 2130 is
provided for each of the arms 2103R and 2103L. However, the
embodiment is not limited thereto and two or more sensors may be
provided for each of the arms 2130R and 2130L and one or more
sensors may be provided for either the arm 2130R or the arm 2130L.
In this example, as each sensor 2130, the sensor where the quartz
is used as the piezoelectric body is used. However, the embodiment
is not limited thereto and a force sensor that has a piezoelectric
body made of a material having a natural frequency higher than that
of the metallic material to be the structural material forming each
portion of the arms 2103L and 2103R may be used as each sensor
2130.
[0186] As illustrated in FIG. 12, one A/D converter 2131 is
provided in the vicinity of each sensor 2130, in this example, in
the casing of each of the wrist B portions 2109L and 2109R. The A/D
converter 2131 that is provided in the casing of the wrist B
portion 2109L is connected to the sensor 2130 provided on the
external surface of the casing of the wrist B portion 2109L through
a cable (not illustrated in the drawings) and is connected to the
side of the trunk portion 2102 through a cable for a digital signal
(not illustrated in the drawings) that is provided in the casing of
the arm 2130L and has superior flexibility. The A/D converter 2131
converts an output signal (analog signal) of the sensor 2130 input
through the cable into a digital signal and is transmitted to the
side of the trunk portion 2102 through the cable for the digital
signal. The A/D converter 2131 that is provided in the casing of
the wrist B portion 2109R is connected to the sensor 2130 provided
on the external surface of the casing of the wrist B portion 2109R
through a cable (not illustrated in the drawings) and is connected
to the side of the trunk portion 2102 through a cable for a digital
signal (not illustrated in the drawings) that is provided in the
casing of the arm 2103R and has superior flexibility. The A/D
converter 2131 converts an output signal (analog signal) of the
sensor 2130 input through the cable into a digital signal and is
transmitted to the side of the trunk portion 2102 through the cable
for the digital signal. The output signal of each sensor 2130 that
is transmitted to the side of the trunk portion 2102 is input to
the robot controller 2150 through the cable.
[0187] In the robot 2100 that has the above-described
configuration, operations of individual driving portions that
include the actuators Ac2001 to Ac2015 are controlled by the robot
controller 2150. Each of the actuators Ac2001 to Ac2005 is composed
of a decelerator-integrated servo motor that has a hollow portion
where a cable (not illustrated in the drawings) can be inserted,
and the rotation positions of the actuators Ac2001 to Ac2005 are
converted into signals from encoders (not illustrated in the
drawings) incorporated in the actuators Ac2001 to Ac2015 and the
signals are input to the robot controller 2150 through the
cable.
[0188] In this case, in a manufacturing/assembling process of a
mechanical product or an electronic apparatus, a sensory inspection
to evaluate a quality by human five senses (in particular, tactile
sense) and bodily sensation is used when it is inspected whether
the mechanical products or the electronic apparatuses are in a
normal state or an abnormal state (for example, it is inspected
whether there is abnormality). In particular, in a mechanical
product that includes components where plural members such as gears
or couplings are engaged and the torque is transmitted, the sensory
inspection is used when rattling (backlash) is detected.
[0189] FIG. 13 is a diagram illustrating an inspected object
according to the second embodiment.
[0190] In FIG. 13, an inspected object 2140 according to this
embodiment is a mechanical product that includes components engaged
with each other.
[0191] In this case, in the inspected object 2140, when the
inspected object 2140 is abnormal like when processing precision of
the components is low or when assembling precision of the
components is low, the minute change, deformation, and vibration
may be generated in the inspected object 2140. For this reason, in
a manufacturing/assembling process of the inspected object 2140, it
is determined whether the inspected object 2140 is in a normal
state or an abnormal state. However, when it is determined by the
sensory inspection whether the inspected object 2140 is in a normal
state or an abnormal state, because a human sensory organ is used
as a measuring instrument in the sensory inspection, the inspection
result is affected by a skill or a physical condition of an
inspector. Therefore, it is preferable to develop a robot that can
inspect with high precision whether the inspected object 2140 is in
a normal state or an abnormal state without depending on the sensor
inspection.
[0192] The robot 2100 according to this embodiment is a robot that
is made in view of the above requirement, and can inspect whether
the inspected object 2140 is in a normal state or an abnormal state
without depending on the sensor inspection. In this specification,
a state in which the inspected object 2140 is normal is defined as
a normal state and a state in which the inspected object 2140 is
abnormal is defined as an abnormal state. That is, the robot 2100
according to this embodiment can inspect whether the inspected
object 2140 is in a normal state or an abnormal state without
depending on the sensor inspection. Hereinafter, an example of a
predetermined operation that is related to an inspection of
abnormality of the inspected object 2140 executed by the arms 2103L
and 2103R of the robot 2100 in a state in which manufacturing
precision of the inspected object 2140 is set as an inspection
object will be described. In this case, only one of the arms 2103L
and 2103R (in this example, arm 2103R) executes the predetermined
operation. That is, the arm 2103R executes an operation for
rotating the flange 2110R in a state in which a movable portion SH
of the inspected object 2140 is gripped by the hands 2111R, as the
predetermined operation. Thereby, the hands 2111R are rotated by
the rotation of the flange 2110R and the movable portion SH is
rotated by the predetermined rotational number (for example, 4) in
a state where the movable portion is engaged with the engaged
component. In this way, the robot controller 2150 detects whether
there is abnormality in the inspected object 2140, on the basis of
an output signal of the sensor 2130 while the arm 2103R executes
the predetermined operation with respect to the inspected object
2140 (which is described in detail below).
[0193] In this example, the case where the arm 2103R is operated is
described. However, the embodiment is not limited thereto and the
arm 2103L may be operated or both the arms 2103L and 2103R may be
operated in cooperation with each other.
[0194] FIG. 14 is a block diagram illustrating the functional
configuration of the robot controller 2150 according to the second
embodiment. In FIG. 14, for the purpose of easy understanding in
the drawing, the A/D converter 2131 that is provided in the casing
of each of the arms 2103L and 2103R is illustrated outside the
casing.
[0195] In FIG. 14, the robot controller 2150 is composed of a
computer that includes an operator, a storage device, and an input
device (not illustrated in the drawings) and is connected to the
individual driving portions or the individual A/D converts 2131 of
the robot 2100 through the cable to communicate with each other.
The robot controller 2150 has an operation instructing unit 2151, a
position instruction intercepting unit 2152, a smoothing processing
unit 2153, a servo unit 2154, an abnormality detecting unit 2155,
and a gravity torque compensating unit 1157.
[0196] The operation instructing unit 2151 calculates a position
instruction (operation instruction) with respect to each of the
actuators Ac2001 to Ac2015, on the basis of instruction information
with respect to each of the arms 2103L and 2103R instructed through
the input device, and pools the position instruction to the
smoothing processing unit 2153 through the position instruction
intercepting unit 2152.
[0197] The smoothing processing unit 2153 sequentially outputs the
pooled position instruction to the servo unit 2154, for every
predetermined operation cycle.
[0198] The servo unit 2154 has a joint angle feedback circuit Fp
based on a detection value of the encoder of each of the actuators
Ac2001 to Ac2015 and a joint angle feedback circuit Fv based on an
angular speed detection value obtained from the detection value of
the encoder of each of the actuators Ac2001 to Ac2015, for each of
the actuators Ac1001 to Ac1015. The servo unit 2154 generates and
outputs a torque instruction Tref with each of the actuators Ac2001
to Ac2015 for every predetermined operation cycle, on the basis of
the position instructions sequentially input by the smoothing
processing unit 2153.
[0199] The abnormality detecting unit 2155 detects whether there is
abnormality in the inspected object 2140, on the basis of an output
value V of the sensor 2130 converted into the digital signal by the
A/D converter 2131. The abnormality detecting unit 2155 will be
described in detail below.
[0200] When the abnormality of the inspection object 2140 is
detected by the abnormality detecting unit 2155, the position
instruction intercepting unit 2152 intercepts an output of the
position instruction from the operation instructing unit 2151 to
the smoothing processing unit 2153 and intercepts the position
instruction that is transmitted to the servo unit 2154. If the
position instruction transmitted to the servo unit 2154 is
intercepted, a value of the torque instruction Tref that is output
by the feedback decreases and the arms 2103L and 2103R are quickly
stopped.
[0201] The gravity torque compensating unit 2157 adds gravity
compensation torque corresponding to the self weight to the torque
instruction Tref with respect to each of the actuators Ac2001 to
Ac2015 generated by the servo unit 2154.
[0202] FIG. 15 is a block diagram illustrating the functional
configuration of the abnormality detecting unit 2155 according to
the second embodiment.
[0203] In FIG. 15, the abnormality detecting unit 2155 has a
high-pass filter unit 2161, a section setting unit 2162, a
normative waveform recording unit 2163, an output waveform
recording unit 2167, a comparing/determining unit 2164, a zero
point adjusting unit 2165, and a threshold value setting unit
2166.
[0204] The high-pass filter unit 2161 has a high-pass filter (or it
may be a band-pass filter that uses a high frequency band as a
pass-band), and extracts a high frequency vibration component of an
output signal of the sensor 2130 that is amplified by the
amplifying unit 2132 and is converted into the digital signal by
the A/D converter 2131, to remove a frequency component (for
example, frequency component due to disturbance) other than a
frequency due to the abnormality of the inspected object 2140,
which is included in the output signal of the sensor 2130. In the
high-pass filter of the high-pass filter unit 2161, a cutoff
frequency is determined such that the frequency component (for
example, frequency component due to disturbance) other than the
frequency due to the abnormality of the inspected object 2140 can
be removed.
[0205] The section setting unit 2162 sets a section in which the
normative waveform recording unit 2163 records a time history of
the output value V of the sensor 2130 as the normative waveform, on
the basis of input information input by the input device
(hereinafter, simply referred to as "recording section").
[0206] The normative waveform recording unit 2163 records the time
history of the output value V of the sensor 2130 based on the high
frequency vibration component extracted by the high-pass filter
unit 2161 while the arms 2103L and 2103R execute a predetermined
operation corresponding to the recording section set by the section
setting unit 2162 with respect to the inspected object 2140 where
there is no abnormality as a normative waveform (refer to FIG. 16
to be described below). The predetermined operation is an operation
according to the position instruction that is calculated by the
operation instructing unit 2151 on the basis of the instruction
information instructed through the input device.
[0207] The output waveform recording unit 2167 records the time
history of the output value V of the sensor 2130 based on the high
frequency vibration component extracted by the high-pass filter
unit 2161 while the arms 2103L and 2103R perform the predetermined
operation with respect to the inspected object 2140 at the time of
inspecting as an output waveform (refer to FIG. 17 to be described
below.
[0208] The threshold value setting unit 2166 sets a threshold value
Dth that becomes a determination value of generation or
non-generation of the abnormality in the comparing/determining unit
2164, on the basis of the input information input through the input
device.
[0209] The comparing/determining unit 2164 compares the normative
waveform recorded in the normative waveform recording unit 2163 and
the output waveform recorded in the output waveform recording unit
2167, and calculates the difference (in detail, absolute value of
the difference) "D" of the normative waveform and the output
waveform. The number of times (hereinafter, referred to as number
of times of excess N) of the calculated difference "D" exceeding a
threshold value Dth previously set by the threshold value setting
unit 2166 for a constant time (in this example, time needed when
the arms 2103L and 2103R executes the predetermined operation once
with respect to the inspected object 2140) is calculated. The
constant time is not limited to the time needed when the arms 2103L
and 2103R executes the predetermined operation once with respect to
the inspected object 2140. For example, the constant time may be
time that is set through the input device. By determining whether
the number of times of excess N counted for each sensor 1122
exceeds the predetermined number of times of determination Nj, the
comparing/determining unit 2164 determines whether there is
abnormality in the inspected object 2140. Specifically, when the
number of times of excess N is within the predetermined number of
times of determination Nj, the comparing/determining unit 2164
determines that there is no abnormality in the inspected object
2140. When the number of times of excess N exceeds the
predetermined number of times of determination Nj, the
comparing/determining unit 2164 determines that there is
abnormality in the inspected object 2140.
[0210] The zero point adjusting unit 2165 outputs a reset signal to
each sensor 2130 and adjusts a zero point of each sensor 2130,
whenever the arms 2103L and 2103R execute the predetermined
operation corresponding to the recording section set by the section
setting unit 2162 with respect to the inspected object 2140, to
suppress the change in the ambient temperature due to heat
generation of the actuators Ac2002 to Ac2015 of the arms 2103L and
2103R or an influence of the temperature drift of each sensor 2130
generated by self heat generation.
[0211] FIG. 16 is a diagram illustrating an output value V of the
sensor 2130 when the arms 2103L and 2103R according to the second
embodiment execute a predetermined operation with respect to the
inspected object 2140 where there is no abnormality. FIG. 16
illustrates an example of the normative waveform that is recorded
in the normative waveform recording unit 2163 to correspond to the
predetermined operation executed by the arms 2103L and 2103R with
respect to the inspected object 2140 where there is no abnormality,
in which in which a horizontal axis indicates time t and a vertical
axis indicates an output value V of the sensor 2130.
[0212] In FIG. 16, at the time of instructing, the arms 2103L and
2103R executes the predetermined operation according to the
position instruction from the robot controller 2150, with respect
to the inspected object 2140 where there is no abnormality, and
rotates the movable SH by the predetermined rotational number. In
the normative waveform recording unit 2163, the time history of the
output value V of the sensor 1122 while the arms 2103L and 2103R
execute the operation corresponding to the recording section once
with respect to the inspected object 2140 is recorded as the
normative waveform. The normative waveform can always be recorded,
when there is no abnormality in the inspected object 2140. In this
embodiment, an example of the case where the normative waveform is
recorded at the time of instructing the predetermined operation
with respect to the robot 2100 will be described.
[0213] FIG. 17 is a diagram illustrating an output value V of the
sensor 2130 when the arms 2103L and 2103R according to the second
embodiment execute a predetermined operation with respect to the
inspected object 2140 at the time of inspecting. FIG. 17
illustrates an example of the output waveform that is recorded in
the output waveform recording unit 2167 to correspond to the
predetermined operation executed by the arms 2103L and 2103R with
respect to the inspected object 2140 where there is no abnormality
at the time of inspecting, in which in which a horizontal axis
indicates time t and a vertical axis indicates an output value V of
the sensor 2130.
[0214] In FIG. 17, at the time of instructing, the arms 2103L and
2103R executes the predetermined operation according to the
position instruction from the robot controller 2150, with respect
to the inspected object 2140 (in this example, inspected object
2140 where there is no abnormality), and rotates the movable SH by
the predetermined rotational number. In the output waveform
recording unit 2167, the time history of the output value V of the
sensor 2130 while the arms 2103L and 2103R execute the
predetermined operation once with respect to the inspected object
2140 (in this example, inspected object 2140 where there is no
abnormality) is recorded as the output waveform. As in this
example, when there is abnormality in the inspected object 2140
(for example, when processing precision of the components is low or
when assembling precision of the components is high), during the
operation of the arms 2103L and 2103R, a cyclic abnormal vibration
or impact is generated in the inspected object 2140 due to rattling
during a rotation operation. In general, when an abnormal vibration
or impact such as rattling is generated in the inspected object
2140, because the force due to the abnormal vibration or impact is
applied to the arms 2103L and 2103R (the arms 2103L and 2103R are
twisted, the output value V of the sensor 2130 is likely to
increase, as compared with when the abnormal vibration or impact is
not generated. Therefore, when there is abnormality in the
inspected object 2140, a section where the output value V of the
sensor 2130 increases cyclically exists in the output waveform. In
the output waveform that is illustrated in FIG. 17, sections of the
four places where the output value V of the sensor 2130 exist.
[0215] FIGS. 18A and 18B are diagrams illustrating an example of a
method of detecting whether there is abnormality in the inspected
object 2130 according to the second embodiment. FIG. 18A
illustrates the normative waveform corresponding to FIG. 16 and the
output waveform corresponding to FIG. 17, in which a horizontal
axis indicates time t and a vertical axis indicates an output value
V of the sensor 2130. FIG. 18B illustrates a waveform of a
time-series change of the difference "D", in which a horizontal
axis indicates time t and a vertical axis indicates the difference
"D".
[0216] In FIGS. 18A and 18B, as described above, when there is
abnormality in the inspected object 2140, a section where the
output value V of the sensor 2130 increases cyclically exists in
the output waveform. Therefore, by comparing the two waveforms of
the normative waveform at the time of instructing recorded in the
normative waveform recording unit 2163 and the output waveform at
the time of activating recorded in the output waveform recording
unit 2167 in a state where there is no abnormality in the inspected
object 2140, the cyclic change of the output waveform with respect
to the normative waveform can be detected. Therefore, it can be
detected whether there is abnormality in the inspected object 2140.
That is, by determining whether the number of times of excess N
where the difference "D" of the normative waveform and the output
waveform exceeding the threshold value Dth when the arms 2103L and
2103R perform the predetermined operation once with respect to the
injected object 2140 exceeds the number of times of determination
Nj described above, it can be determined whether there is
abnormality in the injected object 2140. Specifically, when the
number of times of excess N is within the number of times of
determination Nj, it can be determined that there is no abnormality
in the injected object 2140. When the number of times of excess N
exceeds the number of times of determination Nj, it can be
determined that there is abnormality in the injected object 2140.
In the examples that are illustrated in FIGS. 18A and 18B, the
number of times of excess N is "4" as illustrated in FIG. 18.
Therefore, when the number of times of determination Nj is "3" or
less, it is determined that there is abnormality in the injected
object 2140.
[0217] FIG. 19 is a flowchart illustrating a control sequence that
is executed by the robot controller 2150 according to the second
embodiment.
[0218] In FIG. 19, a process that is illustrated in a flow is
started when a predetermined operation start manipulation is
executed through the input device. First, in step S2010, the robot
controller 2150 determines whether an operation mode of the robot
2100 is an "instruction mode" to perform instructing or an
"activation mode" to perform activating, on the basis of input
information input through the input device. When the operation mode
of the robot 2100 is the "instruction mode", the determination
result of step S2010 is satisfied and the process proceeds to step
S2020.
[0219] In step S2020, the robot controller 2150 sets the recording
section in the section setting unit 2162, on the basis of the input
information input through the input device.
[0220] Then, in step S2030, the robot controller 2150 outputs the
reset signal to each sensor 2130 and adjusts a zero point of each
sensor 2130, in the zero point adjusting unit 2165.
[0221] Then, the process proceeds to step S2040 and the robot
controller 2150 outputs a position instruction with respect to each
of the actuators Ac2001 to Ac2015, which is calculated in the
operation instructing unit 2151 on the basis of the instruction
information with respect to each of the arms 2103L and 2103R
instructed through the input device, to each of the actuators
Ac2001 to Ac2015, and starts the predetermined operation according
to the corresponding position instruction in the arms 2103L and
2103R, with respect to the inspected object 2140 where there is no
abnormality.
[0222] Then, in step S2050, the robot controller 2150 starts
recording of the normative waveform, in the normative waveform
recording unit 2163. Therefore, while the predetermined operation
corresponding to the recording section set in step S2020 and
started in step S2040 is executed by the arms 2103L and 2103R with
respect to the instructed object 2140, the normative waveform
recording unit 2163 records the time history of the output value V
of each sensor 2130 based on the high frequency vibration component
amplified by the amplifying unit 2132, converted into the digital
signal by the A/D converter 2131, and extracted by each high-pass
filter 2161 as the normative waveform.
[0223] If the arms 2103L and 2103R are operated until the operation
completion position, the process proceeds to step S2060 and the
robot controller 2150 completes the operations of the arms 2103L
and 2103R.
[0224] Then, in step S2070, the robot controller 2150 completes
recording of the normative waveform, in the normative waveform
recording unit 2163. The robot controller 2150 ends the process
that is illustrated in the flow. The process that is illustrated in
the flow is executed by the robot controller 2150, whenever the
predetermined operation start manipulation is executed through the
input device.
[0225] Meanwhile, in step S2010, when the operation mode of the
robot 2100 is the "inspection mode", the determination result of
step S2010 is not satisfied and the process proceeds to step
S2080.
[0226] In step S2080, the robot controller 2150 sets the threshold
value Dth in the threshold value setting unit 2166, on the basis of
the input information input through the input device.
[0227] Then, the process proceeds to step S2090 and the robot
controller 2150 adjusts a zero point of each sensor 2122 in the
zero point setting unit 2165, similar to step S2030.
[0228] Then, in step S2100, the robot controller 2150 outputs a
position instruction with respect to each of the actuators Ac2001
to Ac2015, which is calculated in the operation instructing unit
2151 on the basis of the instruction information with respect to
each of the arms 2103L and 2103R instructed through the input
device, to each of the actuators Ac2001 to Ac2015, and starts the
predetermined operation according to the position instruction in
the arms 2103L and 2103R, with respect to the instructed object
2140.
[0229] Then, the process proceeds to step S2110 and the robot
controller 2150 starts recording of the output waveform for each
sensor 2122, in the output waveform recording unit 2167. Therefore,
while the predetermined operation started in step S2040 is executed
by the arms 2103L and 2103R with respect to the inspected object
2140, the output waveform recording unit 2167 records the time
history of the output value V of the sensor 2130 based on the high
frequency vibration component amplified by the amplifying unit
2123, converted into the digital signal by the A/D converter 2131,
and extracted by the A/D converter 2131 as the output waveform.
[0230] Then, if the arms 2103L and 2103R are operated until the
operation completion position, the process proceeds to step S2120
and the robot controller 2150 completes the operations of the arms
2103L and 2103R.
[0231] Then, the process proceeds to step S2130 and the robot
controller 2150 completes recording of the output waveform, in the
output waveform recording unit 2167.
[0232] Then, in step S2140, the robot controller 2150 compares the
two waveforms of the normative waveform recorded in the normative
waveform recording unit 2163 and the output waveform in the output
waveform recording unit 2167 in the comparing/determining unit
2164, and calculates the difference "D". The robot controller 2150
counts the number of times of excess N where the calculated
difference "D" exceeds the threshold value Dth set in step S2080
when the arms 2103L and 2103R executes the predetermined operation
started in step S2100 and completed in step S2120 once with respect
to the inspected object 2140. By determining whether the number of
times of excess N top be counted exceeds the number of times of
determination Nj, it is determined whether there is abnormality in
the inspected object 2140. Specifically, when the number of times
of excess N is within the predetermined number of times of
determination Nj, it is determined that there is no abnormality in
the inspected object 2140. When the number of times of excess N
exceeds the predetermined number of times of determination Nj, it
is determined that there is abnormality in the inspected object
2140.
[0233] Then, the process proceeds to step S2150 and the robot
controller 2150 determines whether it is determined in step S2140
that there is abnormality in the inspected object 2140. When it is
determined that there is no abnormality in the inspected object
2140, the determination result of step S2150 is not satisfied and
the process that is illustrated in the flow ends. Meanwhile, when
it is determined that there is abnormality in the inspected object
2140, the determination result of step S2150 is satisfied and the
process proceeds to step S2160.
[0234] In step S2160, the robot controller 2150 intercepts the
output of the position instruction from the operation instructing
unit 2151 to the smoothing processing unit 2153 in the position
instruction intercepting unit 2152, outputs the torque instruction
Tref generated by the servo unit 1154 to each of the actuators
Ac2001 to Ac2015, stops the operation instructed to the arms 2103L
and 2103R, and notifies an external device of the abnormality of
the arms 2103L and 2103R in a notifying unit (not illustrated in
the drawings).
[0235] As described above, the robot 2100 according to this
embodiment has the arms 2103L and 2103R. In the vicinity of the
front end of the casing of each of the arms 2103L and 2103R (in
this example, on the external surface of the casing of each of the
twist B portions 2109L and 2109R), the sensor 2130 is provided.
Thereby, the change of the minute force that is generated in the
front ends (hands 2111L and 2111R) of the arms 2103L and 2103R due
to the abnormality of the inspected object 2140 can be detected. As
each sensor 2130, the force sensor that has a piezoelectric body
that has a natural frequency higher than that of the structural
material (metallic material such as iron or aluminum in the above
example) forming each portion of the arms 2103L and 2103R is
provided. Thereby, since the high frequency vibration or the impact
generated in the structural material of each of the arms 2103L and
2103R due to the abnormality of the inspected object 2140 can be
detected, it can be detected with high precision whether there is
abnormality in the inspected object 2140. Since the external force
applied to the arms 2103L and 2103R (for example, hands 2111L and
2111R) can be detected with high precision by the sensor 2130, it
can be detected with high precision whether the robot 2100 is in a
normal state or an abnormal state, that is, whether the object
contacts the arms 2103L and 2103R. Therefore, according to the
robot 2100, it can be detected with high precision whether there is
abnormality in the robot 2100 and the inspected object 2140.
[0236] In this embodiment, particularly, a next effect can be
obtained. That is, the output signal of the sensor 2130 that is
provided in the vicinity of the front end of each of the arms 2103L
and 2103R is transmitted (to the side of the trunk portion 2102)
through the cable provided in the casing of each of the arms 2103L
and 2103R. In this case, the output signal of each sensor 2130 is
an analog signal. At the time of transmitting the analog signal, a
coaxial cable is generally used to suppress noise. However, since
the coaxial cable has inferior flexibility, the signals may be
erroneously transmitted when the arms 2103L and 2103R are bent.
Therefore, in this embodiment, the A/D converter 2131 that converts
the output signal of the sensor 2130 into the digital signal is
provided in the vicinity of the front end of each of the arms 2103L
and 2103R (in casing of each of the twist B portions 2109L and
2109R in the above example). Thereby, a cable for a digital signal
that has superior flexibility can be provided in the casing of each
of the arms 2103L and 2103R. Therefore, the output signal of the
sensor 2130 can be securely transmitted without depending on the
operation of the arms 2103L and 2103R and reliability can be
improved.
[0237] In this embodiment, particularly, the sensor 2130 is
provided on the external surface of the casing of each of the twist
B portions 2109L and 2109R. Thereby, an arrangement space of the
sensor 2130 does not need to be secured in the casing of each of
the arms 2103L and 2103R, and the thickness of the front ends of
the arms 2103L and 2103R can be prevented from increasing.
[0238] In this embodiment, particularly, each sensor 2130 is the
sensor where the quartz is used as the piezoelectric body. By using
the sensor where the quartz is used as the piezoelectric body as
each sensor 2130, the high frequency vibration that is generated in
the casing of each of the arms 2103L and 2103R due to abnormality
of the inspected object 2140 can be securely detected. Therefore,
it can be detected with high precision whether there is abnormality
in the inspected object 2140.
[0239] The second embodiment has been described. However, the
embodiment may be implemented by various different embodiments
other than the second embodiment. Therefore, the various different
embodiments are hereinafter described as modifications.
[0240] (1) Case where the Robot is Applied to Detection of a
Contact of an Object
[0241] In the above embodiment, the robot disclosed in the present
application is applied to the detection of the abnormality of the
inspected object 2140. However, the embodiment is not limited
thereto and the robot disclosed in the present application may be
applied to detection of a contact of the object with respect to the
arms 2103L and 2103R.
[0242] FIG. 20 is a top view illustrating the configuration of a
robot 2100 according to this modification. FIG. 20 corresponds to
FIG. 12 described above. The same components as those of FIG. 12
are denoted by the same reference numeral and the description
thereof is appropriately described.
[0243] As illustrated in FIG. 20, the robot 2100 according to this
modification is different from the robot 2100 according to the
second embodiment in that two sensor units 2120L and 2120R are
additionally provided. Each of the sensor units 2120L and 2120R
includes a disk-shaped sensor fixing jig 2121 and at least one
sensor 2122 (second strain sensor) (in this example, three sensors)
that has an approximately rectangular solid shape. The sensor
fixing jig 2121 of the sensor unit 2120L is attached to a base of a
stator of the actuator Ac2002 of the arm 2103L that is positioned
to be closest to the side of the base end, and each sensor 2122
that is provided in the sensor fixing jig 2121 can detect the force
applied the arm 2103L (in detail, amount of strain caused by a
vibration due to the impact force applied to the arm 2103L, not the
magnitude of the force). The sensor fixing jig 2121 of the sensor
unit 2120R is attached to a base of a stator of the actuator Ac2002
of the arm 2103R that is positioned to be closest to the side of
the base end, and each sensor 2122 that is provided in the sensor
fixing jig 2121 can detect the force applied the arm 2103R (in
detail, amount of strain caused by a vibration due to the impact
force applied to the arm 2103R, not the magnitude of the
force).
[0244] In this modification, as each sensor 2122, a force sensor
that has a piezoelectric body made of a material having a natural
frequency (or rigidity) higher than that of the metallic material
to be the structural material forming each portion of the arms
2103L and 2103R, in this example, a sensor where the quartz is used
as the piezoelectric body is used. Each sensor 2122 is not limited
to the sensor where the quartz is used as the piezoelectric body,
and may be the force sensor that has a piezoelectric body having a
natural frequency higher than that of the metallic material to be
the structural material forming each portion of the arms 2103L and
2103R. Each sensor 2122 of the sensor unit 2120L detects the amount
of strain of a radial direction of the sensor fixing jig 2121 due
to the force applied to the arm 2103L as a voltage and each sensor
2122 of the sensor unit 2120R detects the amount of strain of a
radial direction of the sensor fixing jig 2121 due to the force
applied to the arm 2103R as a voltage. The voltage that is obtained
by each sensor 2122 is amplified by the amplifying unit 2132 and is
input to the high-pass filter unit 2161.
[0245] The other configuration is the same as that of the robot
2100 according to the second embodiment. In this modification, a
contact detecting unit (not illustrated in the drawings) of the
robot controller 2150 detects whether the object contacts the arms
2103L and 2103R, on the basis of the output value V (output signal)
of each sensor 2122 of the sensor units 2120L and 2120R. In this
specification, the object is defined as a meaning including the
inspected object 2140, the robot 2100, a work apparatus, a part of
a building such as a wall, and an organism such as a living
body.
[0246] That is, as described above, each sensor 2122 of the sensor
units 2120L and 2120R detects the force that is applied to the arms
2103L and 2103R. As the force that is applied to the arms 2103L and
2103R, the internal force that is generated by the operation of the
arms 2103L and 2103R and the external force that is applied to the
arms 2103L and 2103R from the outside are considered. The external
force is not applied to the arms 2103L and 2103R when the arms
2103L and 2103R are operated in a state in which the object does
not contact the arms 2103L and 2103R. Therefore, each sensor 2122
detects only the vibration due to the internal force. Meanwhile,
when the object contacts the arms 2103L and 2103R, the internal
force and the external force are applied to the arms 2103L and
2103R. Therefore, each sensor 2122 detects the vibrations due to
the internal force and the external force. For this reason, when
the object contacts the arms 2103L and 2103R, the output value V of
the sensor 2122 increases by the amount corresponding to the
external force. Therefore, in this modification, the contact
detecting unit compares output data of the output value V of the
sensor 2122 when the arms 2103L and 2103R execute the predetermined
operation with respect to the inspected object 2140 at the time of
inspecting and the normative waveforms previously recorded as the
time history of the output value V of the sensor 2122 while the
arms 2103L and 2103R execute the predetermined operation with
respect to the inspected object 2140 in a state in which the object
does not contact the arms 2103L and 2103R, and determines whether
the object contacts the arms 2103L and 2103R.
[0247] FIG. 21 schematically illustrates an example of the
predetermined operation that is executed by the arms 2103L and
2103R with respect to the inspected object 2140 at the time of
inspecting. In the example that is illustrated in FIG. 21, at the
time of inspecting, under an environment in which an obstacle B
exists around the robot 2100 (within the movable range of the arms
2103L and 2103R), the arms 2103L and 2103R perform the
predetermined operation according to the position instruction from
the robot controller 2150, with respect to the inspected object
2140. At this time, the contact detecting unit compares the output
data of the output value V of each sensor 2122 and the previously
recorded normative waveform and determines whether the object
contacts the arms 2103L and 2103R. When the contact detecting unit
detects the contact of the object (obstacle B in this example) with
respect to the arms 2103L and 2103R during a period until the arms
2103L and 2103R completes the predetermined operation, the robot
controller 2150 stops the operation of the arms 2103L and 2103R at
the corresponding position (position illustrated at the right side
of FIG. 21).
[0248] In this example, the case where the contact of the obstacle
B with respect to the arms 2103L and 2103R is detected and the
operation is stopped when the contact is detected is described.
However, the embodiment is not limited thereto and the contact of
the inspected object 2140 with respect to the arms 2103L and 2103R
may be detected, the operation may be stopped when the contact is
detected, and the product P may be gripped by the hands 2111L and
2111R.
[0249] In this modification described above, the sensor 2122 that
has a piezoelectric body having a natural frequency higher than
that of the metallic material to be the structural material forming
each portion of the arms 2103L and 2103R is provided in the bases
of the actuators Ac2002 and Ac2009 of the arms 2103L and 2103R
closest to the side of the base end. Since the external force
applied to the arms 2103L and 2103R can be detected by the sensor
2122, it can be detected whether the object contacts the arms 2103L
and 2103R. Since the sensor 2122 is provided in the bases of the
actuators Ac2002 and Ac2009 of the arms 2103L and 2103R closest to
the side of the base end, a contact at the side of the front end
thereof can be detected. That is, a contact with respect to the
entire arms 2103L and 2103R can be detected. Therefore, excessive
load can be avoided from being applied to the robot 2100 or the
object existing around the robot 2100.
[0250] (2) Case where the Robot is Applied to Detection of
Abnormality of the Arms
[0251] In the above embodiment, the robot disclosed in the present
application is applied to detection of abnormality of the inspected
object 2140 and detection of a contact of the object with respect
to the arms 2103L and 2103R. However, the embodiment is not limited
thereto and the robot disclosed in the present application may be
applied to detection of abnormality of the arms 2103L and
2103R.
[0252] The configuration of the robot 2100 according to this
modification is the same as that of the robot 2100 according to the
modification of (1). In this modification, the robot controller
2150 detects generation or non-generation based on aging of a
rotation member such as the actuators Ac2002 to Ac2015 provided in
the arms 2103L and 2103R and the decelerator, on the basis of an
output value V (output signal) of each sensor 2122 of the sensor
units 2120L and 2120R. However, the embodiment is not limited
thereto and the robot controller 2150 may detect generation or
non-generation (including abnormality based on aging of the
rotation member such as the actuators Ac2002 to Ac2015 or the
decelerator or abnormality of the casings of the arms 2103L and
2103R) of the arms 2103L and 2103R.
[0253] In this case, when the abnormality based on aging is
generated in a rotation member such as the actuators Ac2002 to
Ac2015 of the arms 2103L and 2103R and the decelerator, an abnormal
place cyclically appears in a rotation phase. For this reason, when
the arms 2103L and 2103R are operated, a cyclic abnormal vibration
or impact is easily generated. In general, when the cyclic abnormal
vibration or impact is generated in the arms 2103L and 2103R,
because the force due to the cyclic abnormal vibration or impact is
transmitted to the arms 2103L and 2103R (the arms 2103L and 2103R
are twisted), the output value V of the sensor 2122 is likely to
increase, as compared with when the abnormal vibration or the
impact is not generated. Therefore, when the abnormality based on
aging is generated in a rotation member such as the actuators
Ac2002 to Ac2015 of the arms 2103L and 2103R and the decelerator, a
section where the output value V of the sensor 1122 increases
cyclically exists in the output waveform that is the time history
of the output value of the sensor 2122. Therefore, in this
modification, the robot controller 2150 compares the normative
waveform to be the time history of the output value V of each
sensor 2122 previously recorded in a state where there is no
abnormality in the arms 2103L and 2103R and the output waveform to
be the time history of the output value V of each sensor 2122 while
the arms 2103L and 2103R execute the predetermined operation once
with respect to the inspected object 2140 at the time of
inspecting, detects the cyclic change of the output waveform with
respect to the normative waveform, and determines whether there is
abnormality in the actuators Ac2002 to Ac2015 of the arms 2103L and
2103R.
[0254] In this modification, a next effect can be obtained. That
is, by providing the sensors 2122 having the piezoelectric body
having a natural frequency higher than that of the structural
material forming each portion of the arms 2103L and 2103R, the high
frequency abnormal vibration or the impact that is generated in the
structural material of each portion of the arms 2103L and 2103R due
to the abnormality based on the aging of the rotation member such
as the actuators Ac2002 to Ac2015 of the arms 2103L and 2103R and
the decelerator can be detected, and it can be detected whether
there is abnormality in the arms 2103L and 2103R. Since the sensors
2122 are provided in the bases of the actuators Ac2002 and Ac2009
of the arms 2103L and 2103R closest to the side of the base end,
the abnormal vibration based on the rotation member such as all of
the actuators at the side of the front end thereof or the
decelerator can be detected. That is, abnormality with respect to
the entire arms 2103L and 2103R can be detected.
[0255] In this embodiment, particularly, as each sensor 2122, the
sensor where the quartz is used as the piezoelectric body is used.
Thereby, the high frequency abnormal vibration or the impact that
is generated in the structural material of each portion of the arms
2103L and 2103R due to the abnormality based on the aging of the
rotation member such as the actuators Ac2002 and Ac2009 of the arms
2103L and 2103R or the decelerator can be securely detected.
Therefore, it can be detected with high precision whether there is
abnormality in the arms 2103L and 2103R.
[0256] (3) Case where the Robot is Applied to a Single-Arm
Robot
[0257] In the above embodiment, the robot disclosed in the present
application is applied to the robot 2100 to be the dual-arm robot
that has the two arms 2103L and 2103R. However, the embodiment is
not limited thereto and the robot disclosed in the present
application may be applied to a single-arm robot that has one robot
arm. Even in this case, the same effect as that of the above
embodiment can be obtained.
[0258] (4) Others
[0259] In the above embodiment, the mechanical product that
includes the components engaged with each other is used as the
inspection object. However, the embodiment is not limited thereto
and various mechanical products or electric products may be used as
inspection objects.
[0260] For example, the robot according to this embodiment may be
applied to detection of abnormality of a closing state of a plastic
cover or detection of abnormality of an operation button of a
cellular phone.
[0261] In the above embodiment, the configuration where only the
robot controller 2150 is provided as the control system is used. A
control device that has a function as a contact detecting unit
connected to a sensor system may be provided separately from the
robot controller 2150 to control an operation of the robot 2100 to
form one control system.
[0262] In addition to the configuration described above, the
configuration where the methods according to the embodiment and the
modifications are appropriately combined may be used.
[0263] Although not specifically described, this embodiment can be
variously changed in a range that does not depart from the sprit
and scope of the embodiment.
[0264] Next, a third embodiment will be described.
[0265] In a field of robots, it is preferable to avoid an excessive
load from being generated with respect to a robot or an object
existing around the robot. For this reason, various technologies
for detecting generation or non-generation of a contact (external
force) with respect to the robot are studied.
[0266] For example, a technology for attaching a force detector to
detect the external force to a base end of a robot arm and stopping
an operation of the robot arm on the basis of the detection result
of the force detector or operating the robot arm in a reduction
direction of the external force when the excessive external force
is applied is disclosed in Japanese Patent Application Laid-Open
(JP-A) No. 2006-21287.
[0267] In the related art, it is preferable to detect a contact or
a non-contact with respect to the robot arm with high precision in
order to improve functionality of the robot.
[0268] In the related art, the actual external force that is
applied to the robot arm is calculated by subtracting the internal
force generated by an operation of the robot arm from the force
detected by the force detector. For this reason, responsiveness
with respect to the contact of the robot arm is late. In the case
of a slight contact or a momentary contact, the contact may not be
detected with high precision.
[0269] According to one aspect of an embodiment, a robot system
that can improve functionality of a robot and a robot state
determining method are provided.
[0270] According to this embodiment, the functionality of the robot
can be improved.
[0271] Hereinafter, the third embodiment will be described with
reference to the drawings. This embodiment is an example of the
case where the robot system and the robot state determining method
disclosed in the present application is applied to product grip
control based on a dual-arm robot having two robot arms.
[0272] FIG. 22 is a conceptual diagram illustrating the entire
configuration of the robot system according to the third
embodiment. FIG. 23 is a top view illustrating the configuration of
the robot according to the third embodiment.
[0273] In FIGS. 22 and 23, a robot system 3001 according to this
embodiment is a system that includes a robot 3001 provided on one
side of a belt conveyor 3002 to convey plural products P and a
robot controller 3150 (control unit) to control the robot 3100. The
robot 3100 is a dual-arm robot and has a base 3101, a trunk portion
3102, two arms 3103L and 3103R (robot arms), and two sensor units
3120L and 3120R.
[0274] The base 3101 is fixed to a mounting surface (floor) by an
anchor bolt (not illustrated in the drawings). The trunk portion
3102 has a first joint portion in which an actuator Ac3001 driven
to rotate around a rotation axis Ax3001 is provided. The trunk
portion 3102 is disposed to rotate with respect to the base 3101
through the first joint portion and rotates in a direction
approximately horizontal to the mounting surface by driving of the
actuator Ac3001 provided in the first joint portion. The trunk
portion 3102 supports the arms 3103L and 3103R that are configured
as separate objects, at one side (right side in FIGS. 22 and 23)
and the other side (left side in FIGS. 22 and 23),
respectively.
[0275] The arm 3103L is a manipulator that is provided on one side
of the trunk portion 3102. The arm 3103L has a shoulder portion
3104L, an upper arm A portion 3105L, an upper arm B portion 3106L,
a lower arm portion 3107L, a wrist A portion 3108L, a wrist B
portion 3109L, a flange 3110L, a hand 3111L, and second to eighth
joint portions in which actuators Ac3002 to Ac3008 to drive
rotation of the individual portions are provided, respectively.
[0276] The shoulder portion 3104L is connected to the trunk portion
3102 to rotate through the second joint portion and rotates around
a rotation axis Ax3002 approximately horizontal to the mounting
surface by driving of the actuator Ac3002 provided in the second
joint portion. The upper arm A portion 3105L is connected to the
shoulder portion 3104L to rotate through the third joint portion
and rotates around a rotation axis Ax3003 orthogonal to the
rotation axis Ax3002 by driving of the actuator Ac3003 provided in
the third joint portion. The upper arm B portion 3106L is connected
to a front end of the upper arm A portion 3105L shoulder portion
3104L to rotate through the fourth joint portion and rotates around
a rotation axis Ax3004 orthogonal to the rotation axis Ax3003 by
driving of the actuator Ac3004 provided in the fourth joint
portion. The lower arm portion 3107L is connected to the upper arm
B portion 3106L to rotate through the fifth joint portion and
rotates around a rotation axis Ax3005 orthogonal to the rotation
axis Ax3004 by driving of the actuator Ac3005 provided in the fifth
joint portion. The wrist A portion 3108L is connected to a front
end of the lower arm portion 3107L to rotate through the sixth
joint portion and rotates around a rotation axis Ax3006 orthogonal
to the rotation axis Ax3005 by driving of the actuator Ac3006
provided in the sixth joint portion. The wrist B portion 3109L is
connected to the wrist A portion 3108L to rotate through the
seventh joint portion and rotates around a rotation axis Ax3007
orthogonal to the rotation axis Ax3006 by driving of the actuator
Ac3007 provided in the seventh joint portion. The flange 3110L is
connected to a front end of the wrist B portion 3109L to rotate
through the eighth joint portion and rotates around a rotation axis
Ax3008 orthogonal to the rotation axis Ax3007 by driving of the
actuator Ac3008 provided in the eighth joint portion. The hand
3111L is attached to a front end of the flange 3110L and rotates
according to the rotation of the flange 3110L.
[0277] The arm 3103R is a manipulator that is provided on the other
side of the trunk portion 3102 and has the same structure as that
of the arm 3103L. The arm 3103R has a shoulder portion 3104R, an
upper arm A portion 3105R, an upper arm B portion 3106R, a lower
arm portion 3107R, a wrist A portion 3108R, a wrist B portion
3109R, a flange 3110R, a hand 3107R, and ninth to fifteenth joint
portions in which actuators Ac3009 to Ac3015 to drive rotation of
the individual portions are provided, respectively.
[0278] The shoulder portion 3104R is connected to the trunk portion
3102 to rotate through the ninth joint portion and rotates around a
rotation axis Ax3009 approximately horizontal to the mounting
surface by driving of the actuator Ac3009 provided in the ninth
joint portion. The upper arm A portion 3105R is connected to the
shoulder portion 3104R to rotate through the tenth joint portion
and rotates around a rotation axis Ax3010 orthogonal to the
rotation axis Ax3009 by driving of the actuator Ac3010 provided in
the tenth joint portion. The upper arm B portion 3106R is connected
to a front end of the upper arm A portion 3105R to be rotatable
through the eleventh joint portion and rotates around a rotation
axis Ax3011 orthogonal to the rotation axis Ax3010 by driving of
the actuator Ac3011 provided in the eleventh joint portion. The
lower arm portion 3107R is connected to the upper arm B portion
3106R to rotate through the twelfth joint portion and rotates
around a rotation axis Ax3012 orthogonal to the rotation axis
Ax3011 by driving of the actuator Ac3012 provided in the twelfth
joint portion. The wrist A portion 3108R is connected to a front
end of the lower arm portion 3107R to rotate through the thirteenth
joint portion and rotates around a rotation axis Ax3013 orthogonal
to the rotation axis Ax3012 by driving of the actuator Ac32013
provided in the thirteenth joint portion. The wrist B portion 3109R
is connected to the wrist A portion 3108R to rotate through the
fourteenth joint portion and rotates around a rotation axis Ax3014
orthogonal to the rotation axis Ax3013 by driving of the actuator
Ac3014 provided in the fourteenth joint portion. The flange 3110R
is connected to a front end of the wrist B portion 3109R to rotate
through the fifteenth joint portion and rotates around a rotation
axis Ax3015 orthogonal to the rotation axis Ax3014 by driving of
the actuator Ac3015 provided in the fifteenth joint portion. The
hand 311R is attached to a front end of the flange 3110R and
rotates according to the rotation of the flange 3110R.
[0279] In this example, each of the arms 3103L and 3103R has seven
joint portions, that is, degrees of freedom of 7 (redundant degree
of freedom). However, the degrees of freedom of each of the arms
3103L and 3103R are not limited to "7".
[0280] As structural materials that form the shoulder portions
3104L and 3104R, the upper arm A portion 3105L and 3105R, the upper
arm B portions 3106L and 3106R, the lower arm portions 3107L and
3107R, the wrist A portions 3108L and 3108R, the wrist B portions
3109L and 3109R, the flanges 3110L and 3110R, and the hands 3111L
and 3111R of the arms 3103L and 3103R, metallic materials such as
iron or aluminum are used.
[0281] As illustrated in FIG. 23, the trunk portion 3102 is formed
to protrude forward in a horizontal direction from the first joint
portion to the second and ninth joint portions, with respect to the
base 3101, such that the rotation axis Ax3001 of the first joint
portion and the rotation axiss Ax3002 and Ax3009 of the second and
ninth joint portions are offset by the length D1 in a direction
approximately horizontal to the mounting surface. Thereby, a space
of the lower side of the shoulder portions 3104L and 3104R can be
used as a work space, and a reachable range of the arms 3103L and
3103R can be enlarged by rotating the rotation axis Ax3001.
[0282] A shape of the upper arm B portion 3106R is set such that
the positions of the rotation axis Ax3001 of the eleventh joint
portion and the rotation axis Ax3012 of the twelfth joint portion
in plan view are offset by the length D2. A shape of the lower arm
portion 3107R is set such that the positions of the rotation axis
Ax3012 of the twelfth joint portion and the rotation axis Ax3013 of
the thirteenth joint portion in plan view are offset by the length
D3. When the rotation axis Ax3011 and the rotation axis Ax3013
takes an approximately horizontal posture, the offset length of the
rotation axis Ax3011 and the rotation axis Ax3013 becomes (D2+D3).
Thereby, when the twelfth joint portion corresponding to a human
"elbow" is bent, clearance of the upper arm A portion 3105R and the
upper arm B portion 3106R corresponding to a human "upper arm" and
the lower arm portion 3107R corresponding to a human "lower arm"
can be greatly secured. Even when the hand 3111R comes close to the
trunk portion 3102, a freedom degree of the arm 3103R at the time
of an operation increases.
[0283] Although not clearly illustrated in FIG. 23, similar to the
arm 3103R, in the arm 3103L, a shape of the upper arm B portion
3106L is set such that the positions of the rotation axis Ax3004 of
the fourth joint portion and the rotation axis Ax3005 of the fifth
joint portion in upper view are offset by the length D2. A shape of
the lower arm portion 3107L is set such that the positions of the
rotation axis Ax3005 of the fifth joint portion and the rotation
axis Ax3006 of the sixth joint portion in upper view are offset by
the length D3. When the rotation axis Ax3004 and the rotation axis
Ax3006 takes an approximately horizontal posture, the offset length
of the rotation axis Ax3004 and the rotation axis Ax3006 becomes
(D2+D3).
[0284] As illustrated in FIG. 23, each of the sensor units 3120L
and 3120R includes a disk-shaped sensor fixing jig 3121 and at
least one sensor 3122 (second strain sensor) (in this example,
three sensors) that has an approximately rectangular solid shape.
The sensor fixing jig 3121 of the sensor unit 3120L is attached to
a base of a stator of the actuator Ac3002 of the arm 3103L that is
positioned to be closest to the side of the base end, and each
sensor 3122 that is provided in the sensor fixing jig 3121 can
detect the force applied the arm 3103L (in detail, amount of strain
caused by a vibration due to the impact force applied to the arm
3103L, not the magnitude of the force). The sensor fixing jig 3121
of the sensor unit 3120R is attached to a base of a stator of the
actuator Ac2002 of the arm 3103R that is positioned to be closest
to the side of the base end, and each sensor 3122 that is provided
in the sensor fixing jig 3121 can detect the force applied the arm
3103R (in detail, amount of strain caused by a vibration due to the
impact force applied to the arm 3103R, not the magnitude of the
force). The sensor units 3120L and 3120R will be descried in detail
below.
[0285] In the robot 3100 that has the above-described
configuration, operations of individual driving portions that
include the actuators Ac3001 to Ac3015 are controlled by the robot
controller 3150, such that the operation is stopped and the product
P is gripped by the hands 3111L and 3111R, when the arms 3103L and
3103R are operated toward the inner side more than both sides of
the product P on the belt conveyor 3002 and a contact of the object
with respect to the arms 3103L and 3103R is detected. Each of the
actuators Ac3001 to Ac3015 is composed of a decelerator-integrated
servo motor that has a hollow portion where a cable (not
illustrated in the drawings) can be inserted, and the rotation
positions of the actuators Ac3001 to Ac3015 are converted into
signals from encoders (not illustrated in the drawings)
incorporated in the actuators Ac3001 to Ac3015 and the signals are
input to the robot controller 3150 through the cable.
[0286] FIG. 24 is a block diagram illustrating the functional
configuration of the robot controller 3150 according to the third
embodiment.
[0287] In FIG. 24, the robot controller 3150 is composed of a
computer that includes an operator, a storage device, and an input
device (not illustrated in the drawings) and is connected to each
driving portion or each sensor 3122 of the robot 3100 through the
cable to communicate with each other. The robot controller 3150 has
an operation instructing unit 3151, a position instruction
intercepting unit 3152, a smoothing processing unit 3153, a servo
unit 3154, a contact detecting unit 3155, a grip torque
compensating unit 3156, and a gravity torque compensating unit
3157.
[0288] The operation instructing unit 3151 calculates a position
instruction (operation instruction) with respect to each of the
actuators Ac3001 to Ac3015, on the basis of instruction information
with respect to each of the arms 3103L and 3103R instructed through
the input device, and pools the position instruction to the
smoothing processing unit 3153 through the position instruction
intercepting unit 3152.
[0289] The smoothing processing unit 3153 sequentially outputs the
pooled position instruction to the servo unit 3154, for every
predetermined operation cycle.
[0290] The servo unit 3154 has a joint angle feedback circuit Fp
based on a detection value of the encoder of each of the actuators
Ac3001 to Ac3015 and a joint angle feedback circuit Fv based on an
angular speed detection value obtained from the detection value of
the encoder of each of the actuators Ac3001 to Ac3015, for each of
the actuators Ac3001 to Ac3015. The servo unit 3154 generates and
outputs a torque instruction Tref with each of the actuators Ac3001
to Ac3015 for every predetermined operation cycle, on the basis of
the position instructions sequentially input by the smoothing
processing unit 3153.
[0291] The contact detecting unit 3155 detects whether the robot
3100 is in a normal state or an abnormal state, on the basis of an
output value V of each sensor 31222 of the sensor units 3120L and
3120R. In this specification, a state in which the object does not
contact the arms 3103L and 3103R is defined as a normal state and a
state in which the object contacts the arms 3103L and 3103R is
defined as an abnormal state. Therefore, the object is defined as a
meaning including the robot 3100, a work apparatus such as the belt
conveyor 3002, a part of a building such as a wall, and an organism
such as a living body, in addition to the product P to be the grip
object. That is, in this embodiment, the contact detecting unit
3155 detects whether the object contacts the arms 3103L and 3103R,
on the basis of the output value V (output signal) of each sensor
3122 of the sensor units 3120L and 3120R. The contact detecting
unit 3155 will be described in detail below.
[0292] When a contact of the object with respect to the arms 3103L
and 3103R is detected by the contact detecting unit 3155, the
position instruction intercepting unit 3152 intercepts an output
from the operation instructing unit 3151 to the smoothing
processing unit 3153 and intercepts the position instruction that
is transmitted to the servo unit 3154. If the position instruction
transmitted to the servo unit 3154 is intercepted, a value of the
torque instruction Tref that is output by the feedback decreases
and the arms 3103L and 3103R are quickly stopped.
[0293] The grip torque compensating unit 3156 adds grip
compensation torque corresponding to the self weight to grip the
product P by the arms 3103L and 3103R to the torque instruction
Tref with respect to each of the actuators Ac3001 to Ac3015
generated by the servo unit 3154.
[0294] The gravity torque compensating unit 3157 adds gravity
compensation torque corresponding to the self weight to the torque
instruction Tref with respect to each of the actuators Ac3001 to
Ac3015 generated by the servo unit 3154.
[0295] FIG. 25 is a block diagram illustrating the functional
configuration of the abnormality detecting unit 3155 according to
the third embodiment.
[0296] In FIG. 25, the contact detecting unit 3155 has a high-pass
filter unit 3161, a section setting unit 3162, a normative data
recording unit 3163, a determining unit 3164, a zero point
adjusting unit 3165, and a threshold value setting unit 3166.
[0297] The high-pass filter unit 3161 extracts a high frequency
vibration component of an output signal of each sensor 3122 to
remove a frequency component due to disturbance included in the
output signal of each sensor 3122 of the sensor units 3120L and
3120R. The high-pass filter unit 3161 will be described in detail
below.
[0298] The section setting unit 3162 sets a section in which the
normative data recording unit 3163 records a time history of the
output value V of the sensor unit 3122 as the normative waveform
(normative data), on the basis of input information input by the
input device (hereinafter, simply referred to as "recording
section").
[0299] The normative waveform recording unit 3163 records the time
history of the output value V of each sensor 3122 based on the high
frequency vibration component extracted by the high-pass filter
unit 3161 while the arms 3103L and 3103R execute a predetermined
operation corresponding to the recording section set by the section
setting unit 3162 in a normal state, that is, in a state in which
the object does not contact, as a normative waveform for each
sensor 3122. The predetermined operation is an operation according
to the position instruction that is calculated by the operation
instructing unit 3151 on the basis of the instruction information
(information indicating the operation start position and the
operation completion position) instructed through the input
device.
[0300] The threshold value setting unit 3166 sets a threshold value
Dth that becomes a determination value of a contact or a
non-contact in the determining unit 3164, on the basis of the input
information input through the input device.
[0301] The determining unit 3164 compares output data of the output
value V of each sensor 3122 based on the high frequency vibration
component extracted by the high-pass filter unit 3161 when the arms
3013L and 3013R execute the predetermined operation at the time of
activating and the normative waveform recorded in the normative
data recording unit 3163 for each sensor 3122, for each sensor
3122, and calculates the difference (in detail, absolute value of
the difference) "D" of the output data and the normative waveform
for each sensor 3122. By comparing the difference "D" calculated
for each sensor 3122 and a threshold value Dth previously set by
the threshold value setting unit 3166 for each sensor 3122, the
determining unit 3164 determines whether the robot 3100 is in a
normal state or an abnormal state, that is, whether the object
contacts the arms 3013L and 3103R. The determining unit 3164 will
be described in detail below.
[0302] The zero point adjusting unit 3165 outputs a reset signal to
each sensor 3122 and adjusts a zero point of each sensor 3122,
whenever the arms 3103L and 3103R execute the predetermined
operation corresponding to the recording section set by the section
setting unit 3162, to suppress the change in the ambient
temperature due to heat generation of the actuators Ac3002 to
Ac3015 of the arms 3103L and 3103R or an influence of the
temperature drift of each sensor 3122 generated by self heat
generation.
[0303] FIG. 26 is a diagram illustrating the detailed configuration
of the sensor unit 3120L and 3120R, the high-pass filter unit 3161,
and the determining unit 3164 according to the third
embodiment.
[0304] In FIG. 26, as described above, each of the sensor units
3120L and 3120R includes a disk-shaped sensor fixing jig 3121 and
three sensors 3122 that have an approximately rectangular
parallelepiped shape. The three sensors 3122 of the sensor unit
3120L are disposed on an inner surface of the sensor fixing jig
3121, that is, a surface, (the surface on the left in FIG. 23 and
the surface in front of a plane of paper in FIG. 26), which is not
attached to the base of the stator of the actuator Ac3002, such
that the three sensors 3122 are disposed at an equal interval on
the same circumference and are radially disposed. The three sensors
3122 of the sensor unit 3120R are disposed on the inner surface of
the sensor fixing jig 3121, that is, a surface, (the surface on the
right side in FIG. 23 and surface in front of a plane of paper in
FIG. 26), which is not attached to the base of the stator of the
actuator Ac3009, such that the three sensors 3122 are disposed at
an equal interval on the same circumference and are radially
disposed.
[0305] In this embodiment, a force sensor that has a piezoelectric
body made of a material having a natural frequency (rigidity)
higher than that of the metallic material to be the structural
material forming each portion of the arms 3103L and 3103R, in this
example, a sensor where quartz is used as the piezoelectric body is
used as each sensor 3122. This is because that the change force
including a high frequency component can be detected when a natural
frequency is high and the quartz has a natural frequency (or
rigidity) higher than that of the metallic material to be the
structural material forming each portion of the arms 3103L and
3103R. Therefore, a minute high frequency vibration (fast
deformation and dynamic strain) that is transmitted to the
structural material of each portion of the arms 3103L and 3103R can
be detected.
[0306] Each sensor 3122 is not limited to the sensor where the
quartz is used as the piezoelectric body and may be a force sensor
that has a piezoelectric body made of a material having a natural
frequency higher than that of the metallic material to be the
structural material forming each portion of the arms 3103L and
3103R. Each sensor 3122 of the sensor unit 3120L detects the amount
of strain of a radial direction of the sensor fixing jig 3121 due
to the force applied to the arm 3103L and each sensor 3122 of the
sensor unit 3120R detects the amount of strain of a radial
direction of the sensor fixing jig 3121 due to the force applied to
the arm 3103R. The voltage that is obtained by each sensor 3122 is
amplified by an amplifying unit 3123 and is input to each high-pass
filter 3161A (to be described below) of the high-pass filter unit
3161.
[0307] The high-pass filter unit 3161 has plural high-pass filters
3161A (or band-pass filters using a high frequency band as a
pass-band) that can extract a high frequency vibration component of
the output signal of the sensor 3122, and the high frequency
component of the output signal of each sensor 3122 that is
amplified by the amplifying unit 3123 is extracted by each
high-pass filter 3161A. In each high-pass filter 3161A, a cut-off
frequency is determined to remove a frequency component due to an
event other than a contact such as an operation of the actuators
Ac3002 to Ac3015.
[0308] By comparing the difference "D" calculated for each sensor
3122 at the time of activating with a threshold value Dth
previously set by the threshold value setting unit 3166 for each
sensor 3122, the determining unit 3164 determines whether the
object contacts the arms 3103L and 3103R. Specifically, when among
the difference "D" for each sensor 3122, the difference "D" for
every sensor 3122 is within the threshold value Dth, the
determining unit 3164 determines that the object does not contact
the arms 3103L and 3103R. When the difference "D" for any one of
all of the sensors 3122 exceeds the threshold value Dth, the
determining unit 3164 determines that the object contacts the arms
3103L and 3103R.
[0309] FIGS. 27A and 27B are diagrams illustrating a predetermined
operation that is executed by the arms 3103L and 3103R according to
the third embodiment in a state in which there is no contact
between the arms 3103L and 3103R, and an object, and illustrating
an output value V of the sensor 3122 during the predetermined
operation. FIG. 27A schematically illustrates the predetermined
operation that is executed by the arms 3103L and 3103R in a state
in which the arms 3103L and 3103R do not contact the object. FIG.
27B illustrates a waveform of a time history of the output value V
of the sensor 3122 while the arms 3103L and 3013R execute the
operation illustrated in FIG. 27A, in which a horizontal axis
indicates time t and a vertical axis indicates an output value V of
the sensor 3122
[0310] In FIGS. 27A and 27B, at the time of inspecting, under an
environment in which the product P to be the grip object does not
exist and an object (obstacle) does not exist around the robot 3100
(within the movable range of the arms 3103L and 3103R), that is, in
a state in which the object does not contact the arms 3103L and
3103R, the arms 3103L and 3103R execute the predetermined operation
according to the position instruction from the robot controller
3150, that is, the operation from the instructed operation start
position (position illustrated at the left side of FIG. 27A) to the
instructed operation completion position (position illustrated at
the right side of FIG. 27A). The operation completion position is
set to the position where the hands 3111L and 3111R can grip the
minimum product p among the products P conveyed by the belt
conveyor 3002.
[0311] In this case, as described above, each sensor 3122 of the
sensor units 3120L and 3120R detects the force that is applied to
the arms 3103L and 3103R. As the force that is applied to the arms
3103L and 3103R, the internal force that is generated by the
operation of the arms 3103L and 3103R and the external force that
is applied to the arms 3103L and 3103R from the outside are
considered. The external force is not applied to the arms 3103L and
3103R when the arms 3103L and 3103R are operated in a state in
which the object illustrated in FIG. 27A does not contact the arms
3103L and 3103R. Therefore, each sensor 3122 detects only the
vibration due to the internal force.
[0312] FIGS. 28A and 28B are diagrams illustrating a predetermined
operation that is executed by the arms 3103L and 3103R according to
the third embodiment at the time of activating and an output value
V of the sensor 3122 during the predetermined operation. FIG. 28A
schematically illustrates the predetermined operation that is
executed by the arms 3103L and 3103R at the time of activating.
FIG. 28B illustrates a waveform of a time history of the output
value V of the sensor 3122 while the arms 3103L and 3013R execute
the operation illustrated in FIG. 28A, in which a horizontal axis
indicates time t and a vertical axis indicates an output value V of
the sensor 3122.
[0313] In FIGS. 28A and 28B, at the time of activating, the arms
3103L and 3103R execute the predetermined operation according to
the position instruction from the robot controller 3150, that is,
the operation from the instructed operation start position
(position illustrated at the left side of FIG. 28A) to the
instructed operation completion position (position illustrated at
the right side of FIG. 28A). At this time, the arms 3103L and 3103R
are operated from the operation start position to the inner side
more than both sides of the product P on the belt conveyor 3002
(not illustrated in FIG. 28A). If the contact of the object with
respect to the arms 3103L and 3103R during the operation until the
operation completion position, the arms 3103L and 3103R stop the
operation at the corresponding position such that the product P is
gripped by the hands 3111L and 3111R.
[0314] In this case, the external force is not applied to the arms
3103L and 3103R when the arms 3103L and 3103R are operated in a
state in which the object does not contact the arms 3103L and
3103R. Therefore, each sensor 3122 detects only the vibration due
to the internal force. When the object contacts the arms 3103L and
3103R during the activation (in this example, when the product P
contacts the inner side of the hands 3111L and 3111R), the internal
force and the external force are applied to the arms 3103L and
3103R. Therefore, each sensor 3122 detects the vibration due to the
internal force and the external force. For this reason, as
illustrated in FIG. 28B, when the object contacts the arms 3103L
and 3103R during the activation, the output value V of the sensor
3122 is increased by the amount corresponding to the external
force. The arms 3103L and 3103R stop the operation when the object
contacts the arms 3103L and 3103R and grip the product P.
Therefore, after the object contacts the arms 3103L and 3103R, the
output value V of the sensor 3122 becomes almost a constant value,
as illustrated in FIG. 28B.
[0315] FIGS. 29A and 29B are diagrams illustrating an example of a
method of detecting a contact of an object with respect the arms
3103L and 3103R according to the third embodiment. FIG. 29A
illustrates the normative waveform and a waveform of the time
history of the output value V of the sensor 3122 at the time of
activating, in which a horizontal axis indicates time t and a
vertical axis indicates an output value V of the sensor 3122. FIG.
29B illustrates a waveform of a time-series change of the
difference "D", in which a horizontal axis indicates time t and a
vertical axis indicates the difference "D".
[0316] In FIGS. 29A and 29B, as described above, in the normative
data recording unit 3163, the time history of the output value V of
each sensor 3122 while the arms 3103L and 3103R execute the
predetermined operation corresponding to the recording section set
by the section setting unit 3162 is recorded as the normative
waveform. The normative waveform can always be recorded in a state
in which the object does not contact the arms 3013L and 3103R. In
this embodiment, an example of the case where the normative
waveform is recorded at the time of instructing the predetermined
operation with respect to the robot 3100 will be described. The
normative waveform is data of the time history of the output value
V of the sensor 3122 actually recorded while the arms 3103L and
3103R are operated in a state in which the object does not contact
at the time of instructing. Therefore, the normative waveform
corresponds to the internal force. Therefore, by comparing the
normative waveform and the output data of the output value V of the
sensor 3122 at the time of activating, specifically, calculating
the difference "D" of the output data and the normative waveform,
the external force that is applied to the arms 3013L and 3103R
during the activation can be detected. That is, the difference "D"
corresponds to the external force. By comparing the difference "D"
and the threshold value Dth to be the determination value of a
contact or a non-contact previously set by the threshold value
setting unit 3166, it can be determined whether the external force
is applied to the arms 3103L and 3103R, that is, it can be
determined where the object contacts the arms 3103L and 3103R.
Specifically, when the difference "D" is within the range of the
threshold value Dth, it is determined that the external force is
not applied to the arms 3103L and 3103R, that is, that the object
does not contact the arms 3103L and 3103R. When the difference "D"
exceeds the threshold value Dth, it can be determined that the
external force is applied to the arms 3103L and 3103R, that is,
that the object does not contact the arms 3103L and 3103R.
[0317] The waveform of the time history of the output value V of
the sensor 3122 at the time of activating illustrated in FIG. 29A
is illustrated as an example of a waveform when the object
momentarily contacts (when the external force is not immediately
applied after the contact), like when a ball hits the arms 3103L
and 3103R. According to the above method, a momentary contact can
be detected. As described in this embodiment, when this method is
applied to product grip control based on the dual-arm robot, the
waveform of the time history of the output value V of the sensor
3122 becomes have almost a constant value after the contact, as
described above in FIG. 28B.
[0318] FIG. 30 is a flowchart illustrating a control sequence based
on the robot state determining method that is executed by the robot
controller 3150 according to the third embodiment.
[0319] In FIG. 30, a process that is illustrated in a flow is
started when a predetermined operation start manipulation is
executed through the input device. First, in step S3010, the robot
controller 3150 determines whether an operation mode of the robot
3100 is an "instruction mode" to perform instructing or an
"activation mode" to perform activating, on the basis of input
information input through the input device. When the operation mode
of the robot 3100 is the "instruction mode", the determination
result of step S3010 is satisfied and the process proceeds to step
S3020.
[0320] In step S3020, the robot controller 3150 sets the recording
section in the section setting unit 3162, on the basis of the input
information input through the input device.
[0321] Then, in step S3030, the robot controller 3150 outputs the
reset signal to each sensor 3122 and adjusts a zero point of each
sensor 3122, in the zero point adjusting unit 3165.
[0322] Then, the process proceeds to step S3040 and the robot
controller 3150 outputs a position instruction with respect to each
of the actuators Ac3001 to Ac3015, which is calculated in the
operation instructing unit 3151 on the basis of the instruction
information (information indicating the operation start position
and the operation completion position) with respect to each of the
arms 3103L and 3103R instructed through the input device, to each
of the actuators Ac3001 to Ac3015, and starts the predetermined
operation (refer to FIG. 27A) according to the position instruction
in the arms 3103L and 3103R in a state in which the object does not
contact.
[0323] Then, in step S3050, the robot controller 3150 starts
inputting (acquiring) of the output value V of each sensor 3122 and
starts recording of the normative waveform for each sensor 3122, in
the normative waveform recording unit 3163. Therefore, when the
predetermined operation corresponding to the recording section set
in step S3020 and started in step S3040 is executed by the arms
3103L and 3103R in a state in which the object does not contact,
the output value V of each sensor 3122 based on the high frequency
vibration component amplified by the amplifying unit 3123 and
extracted by each high-pass filter 3161A is input and the normative
data recording unit 3163 records the time history of the input
output value V of each sensor 3122 as the normative waveform for
each sensor 3122.
[0324] If the arms 3103L and 3103R are operated until the operation
completion position, the process proceeds to step S3060 and the
robot controller 3150 completes the operations of the arms 3103L
and 3103R.
[0325] Then, in step S3070, the robot controller 3150 completes the
inputting (acquiring) of the output value V of each sensor 3122 and
completes recording of the normative waveform for each sensor 3122
in the normative waveform recording unit 3163. The robot controller
3150 ends the process that is illustrated in the flow. The process
that is illustrated in the flow is executed by the robot controller
3150, whenever the predetermined operation start manipulation is
executed through the input device.
[0326] Meanwhile, in step S3010, when the operation mode of the
robot 3100 is the "activation mode", the determination result of
step S3010 is not satisfied and the process proceeds to step
S3080.
[0327] In step S3080, the robot controller 3150 sets the threshold
value Dth in the threshold value setting unit 3166, on the basis of
the input information input through the input device.
[0328] Then, the process proceeds to step S3090 and the robot
controller 3150 adjusts a zero point of each sensor 3122 in the
zero point setting unit 3165, similar to step S3030.
[0329] Then, in step S3100, the robot controller 3150 outputs a
position instruction with respect to each of the actuators Ac3001
to Ac3015, which is calculated in the operation instructing unit
3151 on the basis of the instruction information (information
indicating the operation start position and the operation
completion position) with respect to each of the arms 3103L and
3103R instructed through the input device, to each of the actuators
Ac3001 to Ac3015, and starts the predetermined operation according
to the position instruction in the arms 3103L and 3103R (refer to
FIG. 28A).
[0330] Then, the process proceeds to step S3110 and the robot
controller 3150 compares the output data of the input output value
V of each sensor 3122 when the predetermine operation stated in
step S3100 is executed by the arms 3103L and 3103R and the
normative waveform recorded in the normative data recording unit
3163 for each sensor 3122, for each sensor 3122 in the determining
unit 3164, while inputting the output value V of each sensor 3122
based on the high frequency vibration component amplified by the
amplifying unit 3123 and extracted by each high-pass filter 3161A,
and calculates the difference "D" for each sensor 3122. By
comparing the difference "D" calculated for each sensor 3122 and
the threshold value Dth previously set by the threshold value
setting unit 3166 for each sensor 3122, it is determined whether
the object contacts the arms 3013L and 3103R. Specifically, as
described above, when the difference "D" for all of the sensors
3122 is within the threshold value Dth, it is determined that the
object does not contact the arms 3103L and 3103R. When the
difference "D" for one of all of the sensors 3122 exceeds the
threshold value Dth, it is determined that the object contacts the
arms 3103L and 3103R.
[0331] Then, the process proceeds to step S3120 and the robot
controller 3150 determines whether it is determined in step S3110
that the object contacts the arms 3103L and 3103R during the
operation of the arms 3103L and 3103R until the operation
completion position. When it is determined in step S3110 that the
object contacts the arms 3103L and 3103R during the operation of
the arms 3103L and 3103R until the operation completion position,
the determination result of step S3120 is satisfied and the process
proceeds to step S3130.
[0332] In step S3130, the robot controller 3150 intercepts the
output of the position instruction from the operation instructing
unit 3151 to the smoothing processing unit 3153 in the position
instruction intercepting unit 3152, adds the grip compensation
torque to the torque instruction Tref generated by the servo unit
3154, outputs the resultant of the addition to each of the
actuators Ac3001 to Ac3015 to stop the operation in the arms 3103L
and 3103R, and grips the product P by the hands 3111L and 3111R.
Then, the robot controller 3150 ends the process that is
illustrated in the flow.
[0333] Meanwhile, in step S3120, when it is determined in step
S3110 that the object does not contact the arms 3103L and 3103R
during the operation of the arms 3103L and 3103R until the
operation completion position (when the product P to be the grip
object does not exist), the determination result of step S3120 is
not satisfied, the process proceeds to step S3140, and the robot
controller 3150 completes the operation in the arms 3103L and
3103R. The robot controller 3150 ends the process that is
illustrated in the process.
[0334] In the above description, the sequence of steps S3050 and
S3070 corresponds to a normative data recording sequence that is
described in claims and the sequence of step S3110 corresponds to a
determining sequence. The sequence of steps S3050, S3070, and S3110
functions as an output value acquiring sequence.
[0335] As described above, in the robot system 3001 according to
this embodiment, in the normative data recording unit 3163, the
time history of the output value V of each sensor 3122 while the
arms 3103L and 3103R execute the predetermined operation in a state
in which the object does not contact the arms is recorded as the
normative waveform. By comparing the output data of the output
value V of each sensor 3122 when the arms 3103L and 3103R execute
the predetermined operation at the time of activating and the
normative waveform recorded in the normative data recording unit
3163 (comparing the different "D" and the threshold value Dth in
the above example), the determining unit 3164 determines whether
the object contacts the arms 3103L and 3103R. As described above,
the normative waveform is data of the time history of the output
value V of the sensor 3122 actually recorded while the arms 3103L
and 3103R are operated in a state in which the object does not
contact. Therefore, the normative waveform corresponds to the
internal force that is generated by the operation of the arms 3103L
and 3103R. For this reason, by comparing the normative waveform and
the output data of the output value V of the sensor 3122 at the
time of activating, the external force that is applied to the arms
3013L and 3103R during the activation can be detected, and it can
be determined with high precision whether the object contacts the
arms 3103L and 3103R. As a result, control for stopping the
operation of the arms 3103L and 3103R on the basis of whether the
object contacts the arms or operating the arms 3103L and 3103R in a
direction where the external force based on the contact is reduced
can be performed with high precision. Therefore, functionality of
the robot 3100 can be improved.
[0336] In this embodiment, the force sensor that has a
piezoelectric body that has a natural frequency higher than that of
the structural material (metallic material such as iron or aluminum
in the above example) forming each portion of the arms 3103L and
3103R is used as each sensor 3122. In the above example,
particularly, the sensor where the quartz is used as the
piezoelectric body is used as each sensor. Thereby, the high
frequency vibration or the impact that is generated in the
structural material of each portion of the arms 3103L and 3103R due
to collision of the obstacle can be detected, and it can be
detected with high precision whether the object contacts the arms
3103L and 3103R.
[0337] In this embodiment that is applied to the product grip
control, a next effect is obtained. That is, in order to grip an
object having an indefinite shape in the related art, a means for
attaching a special sensor to the hands 3111L and 3111R of the arms
3103L and 3103R and detecting and confirming a grip state needs to
be provided. Meanwhile, in this embodiment, a control operation is
executed such that the two arms 3103L and 3103R are operated toward
the inner side of both sides of the product P, the operation is
stopped when the contact is detected, and the product P is gripped
by the hands 3111L and 3111R. Therefore, the special sensor does
not need to be provided, and product grip control based on the
robot 3100 that has the hands 3111L and 3111R with the simple
configuration and can securely grip the object having the
indefinite shape can be realized.
[0338] In this embodiment, particularly, when the difference "D" of
the output data and the normative waveform is within of the
predetermined threshold value Dth, the determining unit 3164
determines whether the object does not contact the arms 3103L and
3103R. When the difference "D" exceeds the predetermined threshold
value Dth, the determining unit 3164 determines whether the object
contacts the arms 3103L and 3103R. That is, since the difference
"D" of the output data and the normative waveform corresponds to
the external force applied to the arms 3103L and 3103R as described
above, the determining unit 3164 can perform the determination
based on the difference "D" and can detect with high precision
whether the object contacts the arms 3103L and 3103R. By setting
the predetermined threshold value Dth as a determination value of a
contact or a non-contact, erroneous detection based on disturbance
can be suppressed.
[0339] In this embodiment, particularly, the robot controller 3150
has the threshold value setting unit 3166 that sets the threshold
value Dth. Since the threshold value setting unit 3166 can set an
arbitrary value as the threshold value Dth according to a
specification or an activation environment of the robot 3100, the
robot controller 3150 can suppress the erroneous detection based on
the disturbance and can detect with high precision whether the
object contacts the arms 3103L and 3103R.
[0340] In this embodiment, particularly, the robot controller 3150
has the section setting unit 3162 that sets the recording section
where the time history of the output value V of the sensor 3122 is
recorded as the normative waveform by the normative data recording
unit 3163. By the section setting unit 3162, a section where the
arms 3103L and 3103R execute an arbitrary operation can be set as
the recording section. Thereby, a section where the same operation
as the predetermined operation executed by the arms 3103L and 3103R
at the time of activating is executed can be set as the recording
section. If the normative waveform is recorded, it can be securely
detected whether the object contacts the arms 3103L and 3103R.
Since a normative waveform can be recorded for each different
operation, a normative waveform can be recorded to correspond to
each of various operations executed by the arms 3103L and 3103R at
the time of activating.
[0341] In this embodiment, particularly, the robot controller 3150
has the zero point adjusting unit 3165 that adjusts a zero point of
each sensor 3122, whenever the arms 3103L and 3103R execute the
predetermined operation corresponding to the recording section set
by the section setting unit 3162. By the zero point adjusting unit
3165, an influence of the temperature drift of each sensor 3122 can
be suppressed and contact precision can be prevented from being
lowered. In particular, when the arms 3103L and 3103R repeat the
predetermined operation at the time of activating, zero point
adjustment is performed for each operation. Therefore, the
influence of the temperature drift can be securely suppressed.
[0342] In this embodiment, particularly, the robot controller 3150
has the high-pass filter unit 3161 that extracts the high frequency
vibration component of the output signal of each sensor 3122, and
the determining unit 3164 compares the output data of the output
value V of each sensor based on the high frequency vibration
component extracted by the high-pass filter unit 3161 and the
normative waveform and determines whether the object contacts the
arms 3103L and 3103R. Thereby, since the frequency component due to
the disturbance can be removed, it can be detected with high
precision whether the object contacts the arms 3103L and 3103R.
[0343] The third embodiment has been described. However, the
embodiment may be implemented by various different embodiments
other than the third embodiment. Therefore, the various different
embodiments are hereinafter described as modifications.
[0344] (1) Case where the Robot System is Applied to Detection of a
Contact of an Obstacle
[0345] In the above embodiment, the robot system disclosed in the
present application is applied to the product grip control.
However, the embodiment is not limited thereto and the robot system
disclosed in the present application may be applied to detection of
a contact of the obstacle. That is, as illustrated in FIG. 31, the
determining unit 3164 determines whether the obstacle B contacts
the arms 3103L and 3103R using the same method as that of the above
embodiment, when the arms 3103L and 3103R execute the predetermined
operation according to the position instruction from the robot
controller 3150, that is, the operation from the instructed
operation start position (position illustrated at the left side of
FIG. 31) to the instructed operation completion position. If the
contact of the obstacle with respect to the arms 3103L and 3103R is
detected, the operation of the arms 3103L and 3103R is stopped at
the corresponding position (position illustrated at the right side
of FIG. 31). Even in this modification, the same effect as that of
the embodiment can be obtained. Further, it is possible to avoid an
excessive load from acting on a robot 3100 or an object existing
around the robot 3100.
[0346] (2) Case where a Low-Pass Filter is Provided
[0347] In the above embodiment, the high-pass filter unit 3161 that
has the high-pass filter 3161A to extract the high frequency
vibration component of the sensor 3122 is provided in the contact
detecting unit 3155, the determining unit 3164 compares the
normative waveform based on the high frequency vibration component
extracted by the high-pass filter unit 3161 and the output data,
and determines whether the object contacts the arms 3103L and
3103R. However, the embodiment is not limited thereto. That is, a
low-pass filter unit that has a low-pass filter (or it may be a
band-pass filter that uses a high frequency band as a pass-band) to
extract a low frequency vibration component of the output signal of
the sensor 3122 may be provided separately from the high-pass
filter unit 3161, in the contact detecting unit 3155, the
determining unit 3164 may compare the normative waveform based on
the low frequency vibration component extracted by the low-pass
filter unit and the output data, and may determine whether the
object (product including flexibility such as a cardboard box in
particular) contacts the arms 3103L and 3103R. According to this
modification, since the low frequency vibration component can be
extracted, generation or non-generation of a relative late contact,
such as a contact of the product including the flexibility such as
the cardboard box with respect to the arms 3103L and 3103R, can be
detected with high precision.
[0348] Case where the Robot System is Applied to a Single-Arm
Robot
[0349] In the above description, this embodiment is applied to the
robot 3100 to be the dual-arm robot that has the two arms 3103L and
3103R. However, this embodiment may be applied to a single-arm
robot that has one robot arm. Even in this case, the same effect as
that of the above embodiment can be obtained.
[0350] In addition to the configuration described above, the
configuration where the methods according to the embodiment and the
modifications are appropriately combined may be used.
[0351] Although not specifically described, this embodiment can be
variously changed in a range that does not depart from the sprit
and scope of the embodiment.
[0352] Next, a fourth embodiment will be described.
[0353] In a field of robots, it is preferable to avoid an excessive
load from being generated with respect to a robot or an object
existing around the robot. For this reason, various technologies
for detecting generation or non-generation of a contact (external
force) with respect to the robot are studied.
[0354] For example, a technology for attaching a force detector to
detect the external force to a base end of a robot arm and stopping
an operation of the robot arm on the basis of the detection result
of the force detector or operating the robot arm in a reduction
direction of the external force when the excessive external force
is disclosed in Japanese Patent Application Laid-Open (JP-A) No.
2006-21287.
[0355] In order to improve reliability of the robot, it is
preferable to detect generation or non-generation of abnormality in
the robot arm, such as abnormality based on aging of an actuator of
the robot arm or a decelerator.
[0356] In the related art, a six-axial force sensor is used as the
force detector. In general, the six-axial force sensor is
configured using plural strain gauges and a natural frequency is
low. For this reason, a high frequency abnormal vibration that is
generated in the structural material of the robot arm due to the
abnormality of the actuator or the decelerator may not be detected
and the abnormality of the robot arm may not be detected. For this
reason, reliability is low.
[0357] According to one aspect of the embodiment, a robot system
that can detect whether the robot arm is abnormal and can improve
reliability and a robot abnormality detecting method are
provided.
[0358] According to this embodiment, since it can be detected
whether there is abnormality in the robot arm, the reliability of
the robot can be improved.
[0359] The fourth embodiment will be described with reference to
the drawings.
[0360] FIG. 32 is a conceptual diagram illustrating the entire
configuration of the robot system according to the fourth
embodiment. FIG. 33 is a top view illustrating the configuration of
the robot according to the fourth embodiment.
[0361] In FIGS. 32 and 33, a robot system 4001 according to this
embodiment includes a robot 4100 that is provided on one side of a
belt conveyor 4002 to convey plural products P and a robot
controller 4150 (control unit) that controls the robot 4100. The
robot 4100 is a dual-arm robot and includes a base 4101, a trunk
portion 4102, two arms 4103L and 4103R (robot arms), and two sensor
units 4120L and 4120R.
[0362] The base 4101 is fixed to a mounting surface (floor) by an
anchor bolt (not illustrated in the drawings). The trunk portion
4102 has a joint portion in which an actuator Ac4001 driven to
rotate about a rotation axis Ax4001 is provided. The trunk portion
4102 is disposed to rotate with respect to the base 4101 through
the first joint portion and rotates in a direction approximately
horizontal to the mounting surface by driving of the actuator
Ac4001 provided in the first joint portion. The trunk portion 4102
supports the arms 4103L and 4103R that are configured as separate
objects, at one side (right side in FIGS. 32 and 33) and the other
side (left side in FIGS. 32 and 33), respectively.
[0363] The arm 4103L is a manipulator that is provided on one side
of the trunk portion 4102. The arm 4103L has a shoulder portion
4104L, an upper arm A portion 4105L, an upper arm B portion 4106L,
a lower arm portion 4107L, a wrist A portion 4108L, a wrist B
portion 4109L, a flange 4110L, a hand 4111L, and second to eighth
joint portions in which actuators Ac4002 to Ac4008 to drive
rotation of the individual portions are provided, respectively.
[0364] The shoulder portion 4104L is connected to the trunk portion
4102 to rotate through the second joint portion and rotates around
a rotation axis Ax4002 approximately horizontal to the mounting
surface by driving of the actuator Ac4002 provided in the second
joint portion. The upper arm A portion 4105L is connected to the
shoulder portion 4104L to rotate through the third joint portion
and rotates around a rotation axis Ax4003 orthogonal to the
rotation axis Ax4002 by driving of the actuator Ac4003 provided in
the third joint portion. The upper arm B portion 4106L is connected
to a front end of the upper arm A portion 4105L shoulder portion
4104L to rotate through the fourth joint portion and rotates around
a rotation axis Ax4004 orthogonal to the rotation axis Ax4003 by
driving of the actuator Ac4004 provided in the fourth joint
portion. The lower arm portion 4107L is connected to the upper arm
B portion 4106L to rotate through the fifth joint portion and
rotates around a rotation axis Ax4005 orthogonal to the rotation
axis Ax4004 by driving of the actuator Ac4005 provided in the fifth
joint portion. The wrist A portion 4108L is connected to a front
end of the lower arm portion 4107L to rotate through the sixth
joint portion and rotates around a rotation axis Ax4006 orthogonal
to the rotation axis Ax4005 by driving of the actuator Ac4006
provided in the sixth joint portion. The wrist B portion 4109L is
connected to the wrist A portion 4108L to rotate through the
seventh joint portion and rotates around a rotation axis Ax4007
orthogonal to the rotation axis Ax4006 by driving of the actuator
Ac4007 provided in the seventh joint portion. The flange 4110L is
connected to a front end of the wrist B portion 4109L to rotate
through the eighth joint portion and rotates around a rotation axis
Ax4008 orthogonal to the rotation axis Ax4007 by driving of the
actuator Ac4008 provided in the eighth joint portion. The hand
4111L is attached to a front end of the flange 4110L and rotates
according to the rotation of the flange 4110L.
[0365] The arm 4103R is a manipulator that is provided on the other
side of the trunk portion 4102. Similar to the arm 4103L, the arm
4103R has a shoulder portion 4104R, an upper arm A portion 4105R,
an upper arm B portion 4106R, a lower arm portion 4107R, a wrist A
portion 4108R, a wrist B portion 4109R, a flange 4110R, a hand
4107R, and ninth to fifteenth joint portions in which actuators
Ac4009 to Ac4015 to drive rotation of the individual portions are
provided, respectively.
[0366] The shoulder portion 4104R is connected to the trunk portion
4102 to rotate through the ninth joint portion and rotates around a
rotation axis Ax4009 approximately horizontal to the mounting
surface by driving of the actuator Ac4009 provided in the ninth
joint portion. The upper arm A portion 4105R is connected to the
shoulder portion 4104R to rotate through the tenth joint portion
and rotates around a rotation axis Ax4010 orthogonal to the
rotation axis Ax4009 by driving of the actuator Ac4010 provided in
the tenth joint portion. The upper arm B portion 4106R is connected
to a front end of the upper arm A portion 4105R to rotate through
the eleventh joint portion and rotates around a rotation axis
Ax4011 orthogonal to the rotation axis Ax4010 by driving of the
actuator Ac4011 provided in the eleventh joint portion. The lower
arm portion 4107R is connected to the upper arm B portion 4106R to
rotate through the twelfth joint portion and rotates around a
rotation axis Ax4012 orthogonal to the rotation axis Ax4011 by
driving of the actuator Ac4012 provided in the twelfth joint
portion. The wrist A portion 4108R is connected to a front end of
the lower arm portion 4107R to rotate through the thirteenth joint
portion and rotates around a rotation axis Ax4013 orthogonal to the
rotation axis Ax4012 by driving of the actuator Ac4013 provided in
the thirteenth joint portion. The wrist B portion 4109R is
connected to the wrist A portion 4108R to rotate through the
fourteenth joint portion and rotates around a rotation axis Ax4014
orthogonal to the rotation axis Ax4013 by driving of the actuator
Ac4014 provided in the fourteenth joint portion. The flange 4110R
is connected to a front end of the wrist B portion 4109R to rotate
through the fifteenth joint portion and rotates around a rotation
axis Ax4015 orthogonal to the rotation axis Ax4014 by driving of
the actuator Ac4015 provided in the fifteenth joint portion. The
hand 4111R is attached to a front end of the flange 4110R and
rotates according to the rotation of the flange 4110R.
[0367] In this example, each of the arms 4103L and 4103R has seven
joint portions, that is, a freedom degree of 7. However, the
freedom degree of each of the arms 4103L and 4103R is not limited
to "7."
[0368] As structural materials that form the shoulder portions
4104L and 4104R, the upper arm A portion 4105L and 4105R, the upper
arm B portions 4106L and 4106R, the lower arm portions 4107L and
4107R, the wrist A portions 4108L and 4108R, the wrist B portions
4109L and 4109R, the flanges 4110L and 4110R, and the hands 4111L
and 4111R of the arms 4103L and 4103R, metallic materials such as
iron or aluminum are used.
[0369] As illustrated in FIG. 33, the trunk portion 4102 is formed
to protrude forward in a horizontal direction from the first joint
portion to the second and ninth joint portions, with respect to the
base 4101, such that the rotation axis Ax4001 of the first joint
portion and the rotation axiss Ax4002 and Ax4009 of the second and
ninth joint portions are offset by the length D1 in a direction
approximately horizontal to the mounting surface. Thereby, a space
of the lower side of the shoulder portions 4104L and 4104R can be
used as a work space, and a reachable range of the arms 4103L and
4103R can be enlarged by rotating the rotation axis Ax4001.
[0370] A shape of the upper arm B portion 4106R is set such that
the positions of the rotation axis Ax4011 of the eleventh joint
portion and the rotation axis Ax4012 of the twelfth joint portion
in plan view are offset by the length D2. A shape of the lower arm
portion 4107R is set such that the positions of the rotation axis
Ax4012 of the twelfth joint portion and the rotation axis Ax4013 of
the thirteenth joint portion in plan view are offset by the length
D3. When the rotation axis Ax4011 and the rotation axis Ax4013
takes an approximately horizontal posture, the offset length of the
rotation axis Ax4011 and the rotation axis Ax4013 becomes (D2+D3).
Thereby, when the twelfth joint portion corresponding to a human
"elbow" is bent, clearance of the upper arm A portion 4105R and the
upper arm B portion 4106R corresponding to a human "upper arm" and
the lower arm portion 4107R corresponding to a human "lower arm"
can be greatly secured. Even when the hand 4111R comes close to the
trunk portion 4102, a degree of freedom of the arm 4103R at the
time of an operation increases.
[0371] Although not clearly illustrated in FIG. 33, similar to the
arm 4103R, in the arm 4103L, a shape of the upper arm B portion
4106L is set such that the positions of the rotation axis Ax4004 of
the fourth joint portion and the rotation axis Ax4005 of the fifth
joint portion in upper view are offset by the length D2. A shape of
the lower arm portion 4107L is set such that the positions of the
rotation axis Ax4005 of the fifth joint portion and the rotation
axis Ax4006 of the sixth joint portion in upper view are offset by
the length D3. When the rotation axis Ax4004 and the rotation axis
Ax4006 takes an approximately horizontal posture, the offset length
of the rotation axis Ax4004 and the rotation axis Ax4006 becomes
(D2+D3).
[0372] As illustrated in FIG. 33, each of the sensor units 4120L
and 4120R includes a disk-shaped sensor fixing jig 4121 and at
least one (in this example, three) sensor 4122 (strain sensors)
that have an approximately rectangular solid shape. The sensor
fixing jig 4121 of the sensor unit 4120L is attached to a base of a
stator of the actuator Ac4002 of the arm 4103L that is positioned
to be closest to the base side, and the three sensors 4122 that are
provided in the sensor fixing jig 4121 can detect the force applied
the arm 4103L (in detail, amount of strain caused by a vibration
due to the impact force applied to the arm 4103L, not the magnitude
of the force). The sensor fixing jig 4121 of the sensor unit 4120R
is attached to a base of a stator of the actuator Ac4009 of the arm
4103R that is positioned to be closest to the base side, and the
three sensors 4122 that are provided in the sensor fixing jig 4121
can detect the force applied the arm 4103L (in detail, amount of
strain caused by a vibration due to the impact force applied to the
arm 4103R, not the magnitude of the force). The sensor units 4120L
and 4120R will be described in detail below.
[0373] In the robot 4100 that has the above-described
configuration, operations of individual driving portions that
include the actuators Ac4001 to Ac4015 are controlled by the robot
controller 4150, such that the arms 4103L and 4103R are operated
toward the inner side than both sides of the product P on the belt
conveyor 4002 and the product P is gripped by the hands 4111L and
4111R. Each of the actuators Ac4001 to Ac4015 is composed of a
decelerator-integrated servo motor that has a hollow portion where
a wiring line (not illustrated in the drawings) can be inserted,
and the rotation positions of the actuators Ac1001 to Ac1015 are
converted into signals from encoders incorporated in the actuators
Ac4001 to Ac4005 and the signals are input to the robot controller
4150 through the wiring line.
[0374] FIG. 34 is a block diagram illustrating the functional
configuration of the robot controller 4150 according to the fourth
embodiment.
[0375] In FIG. 34, the robot controller 4150 is composed of a
computer (not illustrated in the drawings) that includes an
operator, a storage device, and an input device and is connected to
the individual driving portions of the robot 4100 or the individual
sensors 4122 through the wiring line to communicate with each
other. The robot controller 4150 has an operation instructing unit
4151, a position instruction intercepting unit 4152, a smoothing
processing unit 4153, a servo unit 4154, an abnormality detecting
unit 4155, a grip torque compensating unit 4156, and a gravity
torque compensating unit 4157.
[0376] The operation instructing unit 4151 calculates a position
instruction (operation instruction) with respect to each of the
actuators Ac4001 to Ac4015, on the basis of instruction information
(information indicating the operation start position and the
operation completion position) with respect to each of the arms
4103L and 4103R instructed through the input device, and pools the
position instruction to the smoothing processing unit 4153 through
the position instruction intercepting unit 4152.
[0377] The smoothing processing unit 4153 sequentially outputs the
pooled position instruction to the servo unit 4154, for every
predetermined operation cycle.
[0378] The servo unit 4154 has a joint angle feedback circuit Fp
based on a detection value of the encoder of each of the actuators
Ac4001 to Ac4015 and a joint angle feedback circuit Fv based on an
angular speed detection value obtained from the detection value of
the encoder of each of the actuators Ac4001 to Ac4015, for each of
the actuators Ac4001 to Ac4015. The servo unit 4154 generates and
outputs a torque instruction Tref with each of the actuators Ac4001
to Ac4015 for every predetermined operation cycle, on the basis of
the position instructions sequentially input by the smoothing
processing unit 4153.
[0379] The abnormality detecting unit 4155 detects generation or
non-generation of abnormality based on aging of a rotation member
such as the actuators Ac4002 to Ac4015 provided in the arms 4103L
and 4103R and the decelerator, on the basis of an output value V
(output signal of each sensor 4122 of the sensor units 4120L and
4120R. However, the embodiment is not limited thereto and the
abnormality detecting unit 4155 may detect generation or
non-generation of the abnormality (including abnormality occurring
with aging of the rotating member such as the actuators Ac4002 to
Ac4015 or the decelerator, or abnormality of the casings of the
arms 4103L and 4103R) of the arms 4103L and 4103R. The abnormality
detecting unit 4155 will be described in detail below.
[0380] When the abnormality of the actuators Ac4002 to Ac4015 of
the arms 4103L and 4103R is detected by the abnormality detecting
unit 4155, the position instruction intercepting unit 4152
intercepts an output from the operation instructing unit 4151 to
the smoothing processing unit 4153 and intercepts the position
instruction that is transmitted to the servo unit 4154. If the
position instruction transmitted to the servo unit 4154 is
intercepted, a value of the torque instruction Tref that is output
by the feedback decreases and the arms 4103L and 4103R are quickly
stopped.
[0381] The grip torque compensating unit 4156 adds grip
compensation torque to grip the product P by the arms 4103L and
4103R to the torque instruction Tref with respect to each of the
actuators Ac4001 to Ac4015 generated by the servo unit 4154.
[0382] The gravity torque compensating unit 4157 adds gravity
compensation torque corresponding to the self weight to grip the
product P by the arms 4103L and 4103R to the torque instruction
Tref with respect to each of the actuators Ac4001 to Ac4015
generated by the servo unit 4154.
[0383] FIG. 35 is a block diagram illustrating the functional
configuration of the abnormality detecting unit 4155 according to
the fourth embodiment.
[0384] In FIG. 35, the abnormality detecting unit 4155 has a
high-pass filter unit 4161, a section setting unit 4162, a
normative waveform recording unit 4163, an output waveform
recording unit 4167, a comparing/determining unit 4164, a zero
point adjusting unit 4165, and a threshold value setting unit
4166.
[0385] The high-pass filter unit 4161 extracts a high frequency
vibration component of an output signal of each sensor 4122 to
remove a frequency component (for example, frequency component due
to disturbance) other than a frequency due to the abnormality of
the arms 4103L and 4103R, which is included in the output signal of
each sensor 4122 of the sensor units 4120L and 4120R. The high-pass
filter unit 4161 will be described in detail below.
[0386] The section setting unit 4162 sets a section in which the
normative waveform recording unit 4163 records a time history of
the output value V of the sensor 4122 as the normative waveform, on
the basis of input information input by the input device
(hereinafter, simply referred to as "recording section").
[0387] The normative waveform recording unit 4163 records the time
history of the output value V of each sensor 4122 based on the high
frequency vibration component extracted by the high-pass filter
unit 4161 while the arms 4103L and 4103R execute a predetermined
operation corresponding to the recording section set by the section
setting unit 4162 in a state in which there is no abnormality in
the arms 4103L and 4103R as a normative waveform (refer to FIG. 37B
to be described below) for each sensor 4122. In this case, the
state in which there is no abnormality in the arms 4103L and 4103R
means a state in which there is no structural or functional defect
and failure in the casings (including the structure member, the
cover member, and the wiring line) of the arms 4103L and 4103R and
the actuators Ac4002 to Ac4015 provided in the arms 4103L and 4103R
or the decelerator and the arms and the casing and the actuators or
the decelerator are normally operated, and a contact or
interference not to be intended is not generated in the arms 4103L
and 4103R. For example, the state in which there is no abnormality
in the arms 4103L and 4103R means a state immediately after it is
checked that the casings of the arms 4103L and 4103R and the
actuators Ac4002 to Ac4015 provided in the arms 4013L and 4103R or
the decelerator are normally operated or a state at the time of
initial activating in which there is no initial defect. The
predetermined operation is an operation according to the position
instruction that is calculated by the operation instructing unit
4151 on the basis of the instruction information (information
indicating the operation start position and the operation
completion position) instructed through the input device.
[0388] The output waveform recording unit 4167 records the time
history of the output value V of each sensor 4122 based on the high
frequency vibration component extracted by the high-pass filter
unit 4161 while the arms 4103L and 4103R execute the predetermined
operation at the time of activating as an output waveform (refer to
FIG. 38B to be described below) for each sensor 4122. In this
embodiment, the output waveform recording unit 4167 records the
time history of the output value V of each sensor 4122 while the
arms 4103L and 4103R execute the predetermined operation at the
time of activating as an output waveform for each sensor 4122, when
the product P to be a grip object does not exist in a movable range
at the time of activating (for example, immediately after starting
conveyance of the product P or at the time of stopping the
conveyance and performing checking). However, the embodiment is not
limited thereto and the output waveform recording unit 4167 may
record the time history of the output value V of each sensor 4122
while the arms 4103L and 4103R execute the predetermined operation
at the time of activating in the case where the product P to be a
grip object exists in a movable range at the time of activating as
an output waveform for each sensor 4122.
[0389] The threshold value setting unit 4166 sets a threshold value
Dth that becomes a determination value of generation or
non-generation of the abnormality in the comparing/determining unit
4164, on the basis of the input information input through the input
device.
[0390] The comparing/determining unit 4164 compares the normative
waveform recorded in the normative waveform recording unit 4163 for
each sensor 4122 and the output waveform recorded in the output
waveform recording unit 4167 for each sensor 4122, for each sensor
4122, and calculates the difference (in detail, absolute value of
the difference) "D" of the normative waveform and the output
waveform, for each sensor 4122. The number of times (hereinafter,
referred to as number of times of excess N) of the difference "D"
calculated for each sensor 4122 exceeding a threshold value Dth
previously set by the threshold value setting unit 4166 for a
constant time (in this example, time needed when the arms 4103L and
4103R executes the predetermined operation once) is calculated for
each sensor 4122. The constant time is not limited to the time
needed when the arms 4103L and 4103R executes the predetermined
operation once. For example, the constant time may be time that is
set through the input device. By determining whether the number of
times of excess N counted for each sensor 4122 exceeds the
predetermined number of times of determination Nj for each sensor
4122, the comparing/determining unit 4164 determines whether there
is abnormality in the actuators Ac4002 to Ac4015 of the arms 4103L
and 4103R. The comparing/determining unit 4164 will be described in
detail below.
[0391] The zero point adjusting unit 4165 outputs a reset signal to
each sensor 4122 and adjusts a zero point of each sensor 4122,
whenever the arms 4103L and 4103R execute the predetermined
operation corresponding to the recording section set by the section
setting unit 4162, to suppress the change in the ambient
temperature due to heat generation of the actuators Ac4002 to
Ac4015 of the arms 4103L and 4103R or an influence of the
temperature drift of each sensor 4122 generated by self heat
generation.
[0392] FIG. 36 a diagram illustrating the detailed configuration of
the sensor units 4120L and 4120R, the high-pass filter unit 4161,
and the comparing/determining unit 4164 according to the fourth
embodiment. In FIG. 36, the normative waveform recording unit 4163
and the output waveform recording unit 4167 are not
illustrated.
[0393] In FIG. 36, as described above, each of the sensor units
4120L and 4120R includes the sensor fixing jig 4121 that is
provided on the inner side of the casing of the trunk portion 4102
and is formed in an annular shape and the three sensors 4122 that
are provided in the sensor fixing jig 4121 and have an
approximately rectangular solid shape. The sensor fixing jig 4121
of each of the sensor units 4120L and 4120R has an opening 4121A
where the wiring line of the actuators Ac4002 to Ac4015 provided in
the arms 4103L and 4103R can be inserted, at the approximately
central portion. The three sensors 4122 of the sensor unit 4120L
are disposed on an inner surface of the sensor fixing jig 4121,
that is, a surface (left surface in FIG. 33 and surface in front of
a plane of paper in FIG. 36) not attached to the base of the stator
of the actuator Ac4002, such that the three sensors 4122 are
disposed at an equal interval on the same circumference and are
radially disposed. The three sensors 4122 of the sensor unit 4120R
are disposed on the inner surface of the sensor fixing jig 4121,
that is, a surface (right surface in FIG. 33 and surface in front
of a plane of paper in FIG. 36) not attached to the base of the
stator of the actuator Ac4009, such that the three sensors 4122 are
disposed at an equal interval on the same circumference and are
radially disposed.
[0394] In this embodiment, a force sensor that has a piezoelectric
body made of a material having a natural frequency (rigidity)
higher than that of the metallic material to be the structural
material forming each portion of the arms 4103L and 4103R, in this
example, a sensor where quartz is used as the piezoelectric body is
used as each sensor 4122. This is because that the change force
including a high frequency component can be detected when a natural
frequency is high and the quartz has a natural frequency (or
rigidity) higher than that of the metallic material to be the
structural material forming each portion of the arms 4103L and
4103R. Therefore, a minute high frequency vibration (fast
deformation and dynamic strain) that is transmitted to the
structural material of each portion of the arms 4103L and 4103R can
be detected.
[0395] Each sensor 4122 is not limited to the sensor where the
quartz is used as the piezoelectric body and may be a force sensor
that has a piezoelectric body made of a material having a natural
frequency higher than that of the metallic material to be the
structural material forming each portion of the arms 4103L and
4103R. Each sensor 4122 of the sensor unit 4120L detects the amount
of strain of a radial direction of the sensor fixing jig 4121 due
to the force applied to the arm 4103L as a voltage and each sensor
4122 of the sensor unit 4120R detects the amount of strain of a
radial direction of the sensor fixing jig 4121 due to the force
applied to the arm 4103R as a voltage. The voltage that is obtained
by each sensor 4122 is amplified by an amplifying unit 4123 and is
input to each high-pass filter 4161A (to be described below) of the
high-pass filter unit 4161.
[0396] The high-pass filter unit 4161 has plural high-pass filters
4161A (or band-pass filters using a high frequency band as a
pass-band) that can extract a high frequency vibration component of
the sensor 4122, and the high frequency component of the output
signal of each sensor 4122 that is amplified by the amplifying unit
4123 is extracted by each high-pass filter 4161A. In each high-pass
filter 4161A, a cut-off frequency is determined such that a
frequency component other than a frequency due to abnormality of
the arms 4103L and 4103R (frequency component due to an event other
than a contact such as an operation of the actuators Ac4002 to
Ac4015) can be removed.
[0397] By determining whether the number of times of excess N
counted for each sensor 4122 exceeds the predetermined number of
times of determination Nj for each sensor 4122 described above, the
comparing/determining unit 4164 determines whether there is
abnormality in the actuators Ac4002 to Ac4015 of the arms 4103L and
4103R. Specifically, when the number of times of excess N for all
of the sensors 4122 is within the predetermined number of times of
determination Nj, the comparing/determining unit 4164 determines
that there is no abnormality in the actuators Ac4002 to Ac4015 of
the arms 4103L and 4103R. When the number of times of excess N for
only one sensor 4122 among all of the sensors 4122 exceeds the
predetermined number of times of determination Nj, the
comparing/determining unit 4164 determines that there is
abnormality in the actuators Ac4002 to Ac4015 of the arms 4103L and
4103R. The determination on whether the number of times of excess N
exceeds the predetermined number of times of determination Nj
substantially corresponds to the determination on whether an event
where the difference "D" exceeds the threshold value Dth occurs for
every predetermined cycle. That is, the case in which the number of
occurrences of an event of excess N exceeds the number of times of
determination Nj corresponds to the case in which the event where
the difference "D" exceeds the threshold value Dth occurs for every
predetermined cycle.
[0398] The comparing/determining unit 4164 executes the above
determination while changing the number of times of determination
Nj according to the operation speed of the arms 4103L and 4103R.
That is, in the case where abnormality based on aging is generated
in the rotation member such as the actuators Ac 4002 to Ac4015 of
the arms 4103L and 4103R or the decelerator and a cyclic abnormal
vibration or impact is generated at the time of the operation of
the arms 4103L and 4103R, when the operation speed of the arms
4103L and 4103R is fast, the number of times of generating the
cyclic abnormal vibration increases, and when the operation speed
of the arms 4103L and 4103R is slow, the number of times of
generating the cyclic abnormal vibration decreases. For this
reason, when the number of times of determination Nj is set to a
constant value, erroneous detection of the abnormality is caused
depending on the operation speed. Therefore, in this embodiment,
the comparing/determining unit 4164 executes the above
determination while changing the number of times of determination
Nj according to the operation speed of the arms 4103L and 4103R and
prevents the erroneous detection.
[0399] FIGS. 37A and 37B are diagrams illustrating a predetermined
operation that is executed by the arms 4103L and 4103R according to
the fourth embodiment in a state in which there is no abnormality
and an output value V of the sensor 4122 during the predetermined
operation.
[0400] FIG. 37A schematically illustrates an example of the
predetermined operation that is executed by the arms 4103L and
4103R in a state in which there is no abnormality. In the example
illustrated in FIG. 37A, in a state in which there is no
abnormality in the arms 4103L and 4103R at the time of instructing
and in an environment in which the product P to be the grip object
does not exist and there is no obstacle around in the robot 4100
(within the movable range of the arms 4103L and 4103R), that is, in
a state in which an object does not contact the arms 4103L and
4103R, a predetermined operation according to the position
instruction from the robot controller 4150, that is, an operation
from the instructed operation start position (position illustrated
at the left side of FIG. 37A) to the instructed operation
completion position (position illustrated at the right side of FIG.
37A) is executed. The operation completion position is set to the
position where the hands 4111L and 4111R can grip a minimum portion
of the product P conveyed by the belt conveyor 4002.
[0401] FIG. 37B illustrates an example of the normative waveform
that is recorded in the normative waveform recording unit 4163 to
correspond to the operation illustrated in FIG. 37A, in which a
horizontal axis indicates time t and a vertical axis indicates an
output value V of the sensor 4122. In the example illustrated in
FIG. 37B, in the normative waveform recording unit 4163, the time
history of the output value V of the sensor 4122 while the
operation corresponding to the recording section described above
and illustrated in FIG. 37A is executed once in a state in which
there is no abnormality in the arms 4103L and 4103R is recorded as
the normative waveform. The normative waveform can always be
recorded, when there is no abnormality in the arms 4103L and 4103R.
In this embodiment, an example of the case where the normative
waveform is recorded at the time of instructing the predetermined
operation with respect to the robot 4100 will be described.
[0402] FIGS. 38A and 38B are diagrams illustrating a predetermined
operation that is executed by the arms 4103L and 4103R according to
the first embodiment at the time of activating and an output value
V of the sensor 4122 during the predetermined operation.
[0403] FIG. 38A schematically illustrates an example of the
predetermined operation that is executed by the arms 4103L and
4103R according to the fourth embodiment at the time of activating.
In the example illustrated in FIG. 38A, when the product P to be a
grip object does not exist in a movable range at the time of
activating (for example, immediately after starting conveyance of
the product P or at the time of stopping the conveyance and
performing checking), in a state in which abnormality based on
aging is generated in the rotation member such as the actuators Ac
4002 to Ac4015 of the arms 4103L and 4103R or the decelerator, a
predetermined operation according to the position instruction from
the robot controller 4150, that is, an operation from the
instructed operation start position (position illustrated at the
left side of FIG. 38A) to the instructed operation completion
position (position illustrated at the right side of FIG. 38A) is
executed. In the example that is illustrated in FIG. 38A, the case
where the arms 4103L and 4103R perform the predetermined operation
when the product P to be the grip object does not exist in the
movable range as described above is illustrated. Therefore, similar
to the case of FIG. 37A, the operation from the operation start
position to the operation completion position is executed without
gripping the product P by the hands 4111L and 4111R. Although not
illustrated in the drawings, when the product P to be the grip
object exists, the arms 4103L and 4103R is operated from the
operation start position to the inner side more than both sides of
the product P on the belt conveyor 4002. If the product P contacts
the arms 4103L and 4103R, the arms 4103L and 4103R stop the
operation at the corresponding position such that the product P is
gripped by the hands 4111L and 4111R.
[0404] FIG. 38B illustrates an example of the normative waveform
that is recorded in the output waveform recording unit 4167 to
correspond to the operation illustrated in FIG. 38A, in which a
horizontal axis indicates time t and a vertical axis indicates an
output value V of the sensor 4122. In the example illustrated in
FIG. 38B, in the output waveform recording unit 4167, the time
history of the output value V of the sensor 4122 while the arms
4103L and 4103R execute the operation illustrated in FIG. 38A once
in a state in which abnormality based on aging is generated in the
rotation member such as the actuators Ac4002 to Ac4015 or the
decelerator is recorded as an output waveform. As in this case,
when abnormality based on aging is generated in the rotation member
such as the actuators Ac4002 to Ac4015 of the arms 4103L and 4103R
or the decelerator is recorded as an output waveform, an abnormal
place cyclically appears in a rotation phase. For this reason, when
the arms 4103L and 4103R are operated, a cyclic abnormal vibration
or impact is easily generated. In general, when the cyclic abnormal
vibration or impact is generated in the arms 4103L and 4103R, the
impact force due to the cyclic abnormal vibration or impact is
transmitted to the arms 4103L and 4103R, and the output value V of
the sensor 4122 increases as compared with the case where the
cyclic abnormal vibration or impact is not generated. Therefore,
when abnormality based on aging is generated in the rotation member
such as the actuators Ac4002 to Ac4015 or the decelerator is
recorded as an output waveform, a section where the output value V
of the sensor 4122 increases cyclically exists in the output
waveform. In the output waveform that is illustrated in FIG. 38B,
sections of four places where the output value V of the sensor 4122
increases cyclically exist.
[0405] FIGS. 39A and 39B are diagrams illustrating an example of a
method of detecting whether there is abnormality in the arms 4103L
and 4103R. FIG. 39A illustrates the normative waveform
corresponding to FIG. 37B and the output waveform corresponding to
FIG. 38B, in which a horizontal axis indicates time t and a
vertical axis indicates an output value V of the sensor 4122. FIG.
39B illustrates a waveform of a time-series change of the
difference "D", in which a horizontal axis indicates time t and a
vertical axis indicates the difference "D".
[0406] In FIGS. 39A and 39B, as described above, when there is
abnormality in the arms 4103L and 4103R, a section where the output
value V of the sensor 4122 increases cyclically exists in the
output waveform. Therefore, by comparing the two waveforms of the
normative waveform at the time of instructing recorded in the
normative waveform recording unit 4163 and the output waveform at
the time of activating recorded in the output waveform recording
unit 4167 in a state where there is no abnormality in the arms
4103L and 4103R, the cyclic change of the output waveform with
respect to the normative waveform can be detected. Therefore, it
can be detected whether there is abnormality in the actuators
Ac4002 to Ac4015 of the arms 4103L and 4103R. That is, by
determining whether the number of times of excess N where the
difference "D" of the normative waveform and the output waveform
exceeding the threshold value Dth when the arms 4103L and 4103R
execute the predetermined operation once exceeds the number of
times of determination Nj according to the operation speed of the
arms 4103L and 4103R, it can be determined whether there is
abnormality in the actuators Ac4002 to Ac4015. Specifically, when
the number of times of excess N is within the number of times of
determination Nj, it can be determined that there is no abnormality
in the actuators Ac4002 to Ac4015. When the number of times of
excess N exceeds the number of times of determination Nj, it can be
determined that there is abnormality in the actuators Ac4002 to
Ac4015. In the examples that are illustrated in FIGS. 39A and 39B,
the number of times of excess N is "4" as described above.
Therefore, when the number of times of determination Nj is "3" or
less, it is determined that there is abnormality in the actuators
Ac4002 to Ac4015.
[0407] FIG. 40 is a flowchart illustrating a control sequence based
on a robot abnormality detecting method that is executed by the
robot controller 4150 according to the fourth embodiment.
[0408] In FIG. 40, a process that is illustrated in a flow is
started when a predetermined operation start manipulation is
executed through the input device. First, in step S4010, the robot
controller 4150 determines whether an operation mode of the robot
4100 is an "instruction mode" to perform instructing or an
"activation mode" to perform activating, on the basis of input
information input through the input device. When the operation mode
of the robot 4100 is the "instruction mode", the determination
result of step S4010 is satisfied and the process proceeds to step
S4020.
[0409] In step S4020, the robot controller 4150 sets the recording
section in the section setting unit 4162, on the basis of the input
information input through the input device.
[0410] Then, in step S4030, the robot controller 4150 outputs the
reset signal to each sensor 4122 and adjusts a zero point of each
sensor 4122, in the zero point adjusting unit 4165.
[0411] Then, the process proceeds to step S4040 and the robot
controller 4150 outputs a position instruction with respect to each
of the actuators Ac4001 to Ac4015, which is calculated in the
operation instructing unit 4151 on the basis of the instruction
information (information indicating the operation start position
and the operation completion position) with respect to each of the
arms 4103L and 4103R instructed through the input device, to each
of the actuators Ac4001 to Ac4015, and starts the predetermined
operation (refer to FIG. 37A) according to the position instruction
in the arms 4103L and 4103R, in a state in which there is no
abnormality in the arms 4103L and 4103R and an object does not
contact the arms 4103L and 4103R.
[0412] Then, in step S4050, the robot controller 4150 starts
recording of the normative waveform for each sensor 4122, in the
normative waveform recording unit 4163. Therefore, while the
predetermined operation corresponding to the recording section set
in step S4020 and started in step S4040 is executed in a state in
which there is no abnormality in the arms 4103L and 4103R and an
object does not contact the arms 4103L and 4103R, the normative
waveform recording unit 4163 records the time history of the output
value V of each sensor 4122 which is based on the high frequency
vibration component amplified by the amplifying unit 4123 and
extracted by each high-pass filter 4161A as the normative waveform
for each sensor 4122.
[0413] If the arms 4103L and 4103R are operated until the operation
completion position, the process proceeds to step S4060 and the
robot controller 4150 completes the operations of the arms 4103L
and 4103R.
[0414] Then, in step S4070, the robot controller 4150 completes
recording of the normative waveform for each sensor 4122, in the
normative waveform recording unit 4163. The robot controller 4150
ends the process that is illustrated in the flow. The process that
is illustrated in the flow is executed by the robot controller
4150, whenever the predetermined operation start manipulation is
executed through the input device.
[0415] Meanwhile, in step S4010, when the operation mode of the
robot 4100 is the "activation mode", the determination result of
step S4010 is not satisfied and the process proceeds to step
S4080.
[0416] In step S4080, the robot controller 4150 sets the threshold
value Dth in the threshold value setting unit 4166, on the basis of
the input information input through the input device.
[0417] Then, the process proceeds to step S4090 and the robot
controller 4150 adjusts a zero point of each sensor 4122 in the
zero point setting unit 4165, similar to step S4030.
[0418] Then, in step S4100, the robot controller 4150 outputs a
position instruction with respect to each of the actuators Ac4001
to Ac4015, which is calculated in the operation instructing unit
4151 on the basis of the instruction information (information
indicating the operation start position and the operation
completion position) with respect to each of the arms 4103L and
4103R instructed through the input device, to each of the actuators
Ac4001 to Ac4015, and starts the predetermined operation (refer to
FIG. 38A) according to the position instruction in the arms 4103L
and 4103R, when the product P to be the grip object does not exist
within the movable range of the arms 4103L and 4103R.
[0419] Then, the process proceeds to step S4110 and the robot
controller 4150 starts recording of the output waveform for each
sensor 4122, in the output waveform recording unit 4167. Therefore,
while the predetermined operation started in step S4040 is executed
by the arms 4103L and 4103R when the product P to be the grip
object does not exist within the movable range of the arms 4103L
and 4103R, the output waveform recording unit 4167 records the time
history of the output value V of each sensor 4122 based on the high
frequency vibration component amplified by the amplifying unit 4123
and extracted by each high-pass filter 4161A as the output waveform
for each sensor 4122.
[0420] Then, if the arms 4103L and 4103R are operated until the
operation completion position, the process proceeds to step S4120
and the robot controller 4150 completes the operations of the arms
4103L and 4103R.
[0421] Then, the process proceeds to step S4130 and the robot
controller 4150 completes recording of the output waveform for each
sensor 4122, in the output waveform recording unit 4167.
[0422] Then, in step S4140, the robot controller 4150 compares the
two waveforms of the normative waveform recorded in the normative
waveform recording unit 4163 and the output waveform in the output
waveform recording unit 4167 for each sensor 4122, for each sensor
4122 in the comparing/determining unit 4164, and calculates the
difference "D" for each sensor 4122. The robot controller 4150
counts the number of times of excess N where the difference "D"
calculated for each sensor 4122 exceeds the threshold value Dth set
in step S4080 when the arms 4103L and 4103R executes the
predetermined operation started in step S4100 and completed in step
S4120 once, for each sensor 4122. By determining whether the number
of times of excess N counted for each sensor 4122 exceeds the
number of times of determination Nj set according to the operation
speed of the arms 4103L and 4103R for each sensor 4122, it is
determined whether there is abnormality in the actuators Ac4002 to
Ac4015 of the arms 4103L and 4103R. Specifically, when the number
of times of excess N for all of the sensors 4122 is within the
predetermined number of times of determination Nj, it is determined
that there is no abnormality in the actuators Ac4002 to Ac4015 of
the arms 4103L and 4103R. When the number of times of excess N for
only one sensor 4122 among all of the sensors 4122 exceeds the
predetermined number of times of determination Nj, it is determined
that there is abnormality in the actuators Ac4002 to Ac4015 of the
arms 4103L and 4103R.
[0423] Then, the process proceeds to step S4150 and the robot
controller 4150 determines whether it is determined in step S4140
that there is abnormality in the actuators Ac4002 to Ac4015. When
it is determined that there is no abnormality in the actuators
Ac4002 to Ac4015, the determination result of step S4150 is not
satisfied and the process that is illustrated in the flow ends.
Meanwhile, when it is determined that there is abnormality in the
actuators Ac4002 to Ac4015, the determination result of step S4150
is satisfied and the process proceeds to step S4160.
[0424] In step S4160, the robot controller 4150 intercepts the
output of the position instruction from the operation instructing
unit 4151 to the smoothing processing unit 4153 in the position
instruction intercepting unit 4152, outputs the torque instruction
Tref generated by the servo unit 4154 to each of the actuators
Ac4001 to Ac4015, stops the operation instructed to the arms 4103L
and 4103R, and notifies an external device of the abnormality of
the arms 4103L and 4103R in a notifying unit (not illustrated in
the drawings).
[0425] In the above description, the sequence of steps S4050 and
S4070 corresponds to a normative data recording sequence that is
described in claims, the sequence of steps S4110 and S4130
corresponds to an output data recording sequence, and the sequence
of step S4140 corresponds to a comparing/determining sequence.
[0426] As described above, in the robot system 4001 according to
this embodiment, in the normative data recording unit 4163, the
time history of the output value V of each sensor 4122 while the
arms 4103L and 4103R execute the predetermined operation in a state
in which the object does not contact the arms is recorded as the
normative waveform. In the output data recording unit 4167, the
time history of the output value V of each sensor 4122 while the
arms 4103L and 4103R execute the predetermined operation at the
time of activating is recorded as the output waveform. By comparing
the normative waveform recorded in the normative data recording
unit 4163 and the output waveform recorded in the output data
recording unit 4167 (determining whether the number of times of
excess N exceeding the number of times of determination Nj), the
determining unit 4164 determines whether there is abnormality in
the arms 4103L and 4103R (in the above example, abnormality in the
actuators Ac4002 to Ac4015 provided in the arms 4103L and
4103R).
[0427] In this case, when abnormality based on aging is generated
in the rotation member such as the actuators Ac4002 to Ac4015 or
the decelerator is recorded as an output waveform, an abnormal
place cyclically appears in a rotation phase. For this reason, when
the arms 4103L and 4103R are operated, a cyclic abnormal vibration
or impact is easily generated. The abnormal vibration or the impact
can be detected using the sensor 4122 having the high natural
frequency. Therefore, in this embodiment, since the cyclic change
of the output waveform with respect to the normative waveform can
be detected by comparing the two waveforms of the normative
waveform in a state in which there is no abnormality in the arms
4103L and 4103R and the output waveform at the time of activating,
it can be detected whether there is abnormality in the actuators
Ac4002 to Ac4015 of the arms 4103L and 4103R. Therefore,
reliability of the robot system 4001 can be improved. As a result,
the operation of the arms 4103L and 4103R can be stopped on the
basis of generation or non-generation of the abnormality or the
abnormality can be notified to the outside to quickly perform
maintenance work.
[0428] In this embodiment, particularly, when the number of times
of excess N where the difference "D" of the output waveform and the
normative waveform of each sensor 4122 exceeds the predetermined
threshold value Dth when the arms 4103L and 4103R execute the
predetermined operation once exceeds the predetermined number of
times of determination Nj, the comparing/determining unit 4164
determines that there is abnormality in the actuators Ac4002 to
Ac4015. Thereby, since the cyclic change of the output waveform
with respect to the normative waveform can be securely detected, it
can be detected with high precision whether there is abnormality in
the actuators Ac4002 to Ac4015. By setting the predetermined
threshold value Dth as a determination value of generation or
non-generation of the abnormality, erroneous detection based on
disturbance can be suppressed.
[0429] In this embodiment, particularly, the comparing/determining
unit 4164 perform the above determination while changing the number
of times of determination Nj according to the operation speed of
the arms 4103L and 4103R. Thereby, the erroneous detection can be
prevented from being generated due to the change in the operation
speed, and it can be detected with high precision whether there is
abnormality in the actuators Ac4002 to Ac4015.
[0430] In this embodiment, particularly, the robot controller 4150
has the threshold value setting unit 4166 that sets the threshold
value Dth. Since the threshold value setting unit 4166 can set an
arbitrary value as the threshold value Dth according to a
specification or an activation environment of the robot 4100, the
robot controller 4150 can suppress the erroneous detection based on
the disturbance and can detect whether there is abnormality in the
actuators Ac4002 to Ac4015 with high precision.
[0431] In this embodiment, particularly, the robot controller 4150
has the section setting unit 4162 that sets the recording section
where the time history of the output value V of each sensor 4122 is
recorded as the normative waveform by the normative data recording
unit 4163. By the section setting unit 4162, a section where the
arms 4103L and 4103R execute an arbitrary operation can be set as
the recording section. In this way, if the section where the same
operation as the predetermined operation executed by the arms 4103L
and 4103R is executed os set as the recording section, and the
normative waveform is recorded, it is possible to detect whether
there is abnormality in the actuators Ac4002 to Ac4015 at the time
of activating. Since a normative waveform can be recorded for each
different operation, a normative waveform can be recorded to
correspond to each of various operations executed by the arms 4103L
and 4103R at the time of activating.
[0432] In this embodiment, particularly, the robot controller 4150
has the zero point adjusting unit 4165 that adjusts a zero point of
each sensor 4122, whenever the arms 4103L and 4103R execute the
predetermined operation corresponding to the recording section set
by the section setting unit 4162. By the zero point adjusting unit
4165, an influence of the temperature drift of each sensor 4122 can
be suppressed and abnormality detection precision can be prevented
from being lowered. In particular, when the arms 4103L and 4103R
repeat the predetermined operation at the time of activating, zero
point adjustment is performed for each operation. Therefore, the
influence of the temperature drift can be securely suppressed.
[0433] In this embodiment, particularly, the force sensor that has
a piezoelectric body that has a natural frequency higher than that
of the structural material (metallic material such as iron or
aluminum in the above example) forming each portion of the arms
4103L and 4103R is used as each sensor 4122. Thereby, the high
frequency abnormal vibration or the impact that is generated in the
structural material of each portion of the arms 4103L and 4103R due
to abnormality based on aging of the rotation member such as the
actuators Ac4002 to Ac4015 of the arms 4130L and 4130R or the
decelerator can be detected, and it can be detected with high
precision whether there is abnormality in the actuators Ac4002 to
Ac4015.
[0434] The fourth embodiment has been described. However, the
embodiment may be implemented by various different embodiments
other than the fourth embodiment. Therefore, the various different
embodiments are hereinafter described as modifications.
[0435] (1) Case where the Robot is Applied to Detection of a
Contact of an Object
[0436] In the above embodiment, the robot disclosed in the present
application is applied to the detection of abnormality in the arms
4103L and 4103R. However, the embodiment is not limited thereto and
the robot disclosed in the present application may be applied to
detection of a contact of an object to the arms 4103L and
4103R.
[0437] In this modification, the comparing/determining unit of the
contact detecting unit (not illustrated in the drawings) of the
robot controller 4150 detects whether the robot 4100 is in a normal
state or an abnormal state, on the basis of the output value V
(output signal) of each sensor 4122 of the sensor units 4120L and
4120R. In this specification, a state in which the object does not
contact the arms 4013L and 4103R is defined as a normal state and a
state in which the object contacts the arms 4013L and 4103R is
defined as an abnormal state. Therefore, a subject that can be
recognized as a thing is defined as an object. Accordingly,
examples of the object include a product P to be gripped by the
robot 4100, the robot 4100 itself, a work apparatus such as the
belt conveyor 4002, a part of a building such as a wall, and an
organism such as a living body. That is, in this modification, the
comparing/determining unit of the contact detecting unit detects
whether the object contacts the arms 4103L and 4103R, on the basis
of the output value V (output signal) of each sensor 4122 of the
sensor units 4120L and 4120R.
[0438] In this case, as described above, each sensor 4122 of the
sensor units 4120L and 4120R detects the force that is applied to
the arms 4103L and 4103R. Examples of the force that is applied to
the arms 4103L and 4103R include the internal force that is
generated by the operation of the arms 4103L and 4103R and the
external force that is applied to the arms 4103L and 4103R from the
outside. The external force is not applied to the arms 4103L and
4103R when the arms 4103L and 4103R are operated in a state in
which the object does not contact the arms 4103L and 4103R.
Therefore, each sensor 4122 detects only the vibration due to the
internal force. Meanwhile, when the object contacts the arms 4103L
and 4103R, the internal force and the external force are applied to
the arms 4103L and 4103R. Therefore, each sensor 4122 detects the
vibrations due to the internal force and the external force. For
this reason, when the object contacts the arms 4103L and 4103R, the
output value V of the sensor 4122 increases by the amount
corresponding to the external force. Therefore, in this
modification, the comparing/determining unit of the contact
detecting unit compares the output data of the output value V
(specifically, output value V of the sensor 4122 based on the high
frequency vibration component extracted by the high-pass filter
unit 4161) when the arms 4103L and 4103R execute the predetermined
operation at the time of activating and the normative waveform
previously recorded as the time history of the output value V
(specifically, output value V of the sensor 4122 based on the high
frequency vibration component extracted by the high-pass filter
unit 4161) of the sensor 4122 while the arms 4103L and 4103R
execute the predetermined operation in a state in which the object
does not contact the arms, and determines whether the object
contacts the arms 4103L and 4103R.
[0439] FIG. 41 schematically illustrates an example of the
predetermined operation that is executed by the arms 4103L and
4103R at the time of activating. In the example that is illustrated
in FIG. 41, at the time of activating, under an environment in
which an obstacle B exists around the robot 4100 (within the
movable range of the arms 4103L and 4103R), the arms 4103L and
4103R perform the predetermined operation according to the position
instruction from the robot controller 4150, that is, the operation
from the instructed operation start position (position illustrated
at the left side of FIG. 41) to the instructed operation completion
position. At this time, the contact detecting unit determines
whether the object contacts the arms 4103L and 4103R, using the
above method. The arms 4103L and 4103R are operated from the
operation start position to the inner side more than both sides of
the product P on the belt conveyor 4002 (not illustrated in FIG.
41). When the contact detecting unit detects the contact of the
object (obstacle B in this example) with respect to the arms 4103L
and 4103R while the arms 4103L and 4103R execute the operation
until the operation completion position, the robot controller 4150
stops the operation of the arms 4103L and 4103R at the
corresponding position (position illustrated at the right side of
FIG. 41).
[0440] In this example, the case where the contact of the obstacle
B with respect to the arms 4103L and 4103R is detected and the
operation is stopped when the contact is detected is described.
However, the embodiment is not limited thereto and the contact of
the product P with respect to the arms 4103L and 4103R may be
detected, the operation may be stopped when the contact is
detected, and the product P may be gripped by the hands 4111L and
4111R.
[0441] Even in this modification, the same effect as that of the
above embodiment can be obtained. Since the external force applied
to the arms 4103L and 4103R can be detected by the sensor 4122, it
can be detected whether the object contacts the arms 4103L and
4103R. As described above, since the sensor 4122 is provided in the
bases of the actuators Ac4002 and Ac4009 of the arms 4103L and
4103R closest to the side of the base end, a contact at the side of
the front end can be detected. That is, a contact with respect to
the entire arms 4103L and 4103R can be detected. Therefore,
excessive load can be avoided from being applied to the robot 4100
or the object existing around the robot 4100.
[0442] In particular, the robot controller 4150 has the high-pass
filter unit 4161 that extracts the high frequency vibration
component of the output signal of each sensor 4122, and the
comparing/determining unit of the contact detecting unit compares
the normative waveform based on the high frequency vibration
component extracted by the high-pass filter unit 4161 and the
output waveform and determines whether the object contacts the arms
4103L and 4103R. Thereby, since the frequency component due to the
contact of the object with respect to the arms 4103L and 4103R can
be removed, it can be detected with high precision whether the
object contacts the arms 4103L and 4103R.
[0443] (2) Case where the Robot is Applied to a Single-Arm
Robot
[0444] In the above embodiment, the robot disclosed in the present
application is applied to the robot 4100 to be the dual-arm robot
that has the two arms 4103L and 4103R. However, the embodiment is
not limited thereto and the robot disclosed in the present
application may be applied to a single-arm robot that has one robot
arm. Even in this case, the same effect as that of the above
embodiment can be obtained.
[0445] In addition to the configuration described above, the
configuration where the methods according to the embodiment and the
modifications are appropriately combined may be used.
[0446] Although not specifically described, this embodiment can be
variously changed in a range that does not depart from the sprit
and scope of the embodiment.
[0447] Next, a fifth embodiment will be described.
[0448] In a field of robots, it is preferable to avoid an excessive
load from being generated with respect to a robot or an object
existing around the robot. For this reason, various technologies
for detecting generation or non-generation of a contact (external
force) with respect to the robot are studied.
[0449] For example, a technology for attaching a force detector to
detect the external force to a base end of a robot arm and stopping
an operation of the robot arm on the basis of the detection result
of the force detector or operating the robot arm in a reduction
direction of the external force when the excessive external force
is disclosed in Japanese Patent Application Laid-Open (JP-A) No.
2006-21287.
[0450] Meanwhile, in the related art, if the operation of the robot
arm is stopped after the external force is detected, when the
contacted object is operated, the strong impact force may be
generated, even though the robot arm is stopped. Even when the
robot is operated in a direction where the external force is
reduced, a new operation instruction is generated with respect to
the robot arm after the external force is detected and the robot
arm is operated. For this reason, a response time until the robot
arm is operated after a contact (collision) is generated
increases.
[0451] According to one aspect of the embodiment, a robot system
and a robot control device that can detect the external force
generated due to a contact of the robot arm and an object existing
around the robot arm are provided.
[0452] According to this embodiment, even when disturbance due to a
ripple of a decelerator included in the actuator is applied to the
sensor incorporated in the robot arm, generation or non-generation
and a direction of the external force can be detected without
erroneously detecting the generation or non-generation of the
external force. If the external force is detected, a torque
instruction value with respect to the actuator is limited. If the
external force exceeds the torque instruction value with respect to
each actuator, because the actuator is displaced according to the
external force, the impact that is generated due to a rapid load of
the external force can be alleviated. Even when the external force
is continuously applied to the robot arm, such as when the object
existing around the robot arm continuously move to the robot arm,
the actuator is displaced according to the external force and the
posture of the robot arm is changed. Therefore, the object that
exists around the robot arm can be avoided.
[0453] Hereinafter, the fifth embodiment will be described with
reference to the drawings. This embodiment is an example of the
case where a robot system disclosed in the present application is
applied to a robot system that performs work such as inspection,
sterilization, and milking with respect to a domestic animal, using
a robot arm 5002.
[0454] As illustrated in FIG. 42, a robot system 5100 according to
this embodiment includes a floor F that receives a domestic animal
5001, a robot arm 5002, a controller 5003, and a sensor unit
5004.
[0455] As illustrated in FIG. 43, the robot arm 5002 includes a
base 5040 fixed to a mounting surface (wall surface, floor, or the
like) 5101. The robot arm 5002 further includes a first structural
material 5041, a second structural material 5042, a third
structural material 5043, a fourth structural material 5044, a
fifth structural material 5045, a sixth structural material 5046,
and a flange 5047 that are disposed sequentially from the base 5040
to a front end of the robot arm 5002 are connected to one another
through actuators (rotation joints) driven to rotate.
[0456] The base 5040 and the first structural material 5041 are
connected through a first actuator (first joint) 5041A and the
first structural material 5041 is rotated by driving of the first
actuator 5041A. The first structural material 5041 and the second
structural material 5042 are connected through a second actuator
(second joint) 5042A and the second structural material 5042 is
rotated by driving of the second actuator 5042A.
[0457] The second structural material 5042 and the third structural
material 5043 are connected through a third actuator (third joint)
5043A and the third structural material 5043 is rotated by driving
of the third actuator 5043A. The third structural material 5043 and
the fourth structural material 5044 are connected through a fourth
actuator (fourth joint) 5044A and the fourth structural material
5044 is rotated by driving of the fourth actuator 5044A.
[0458] The fourth structural material 5044 and the fifth structural
material 5045 are connected through a fifth actuator (fifth joint)
5045A and the fifth structural material 5045 is rotated by driving
of the fifth actuator 5045A. The fifth structural material 5045 and
the sixth structural material 5046 are connected through a sixth
actuator (sixth joint) 5046A and the sixth structural material 5046
is rotated by driving of the sixth actuator 5046A.
[0459] The sixth structure 5046 and the flange 5047 are connected
through a seventh actuator (seventh joint) 5047A and the flange
5047 and an end effector 5002A such as a hand that is attached to
the flange 5047 are rotated by driving of the seventh actuator
5047A.
[0460] Various tools (not illustrated in the drawings) such as an
inspector, a milker, and a sterilizer are attached to the end
effect 5002A and perform work such as inspection, sterilization,
and milking, with respect to a target portion 5001A of the domestic
animal 5001.
[0461] To the end effector (that is, front end of the robot arm
5002) 5002A, an object detecting sensor (in this embodiment, the
object detecting sensor is a camera, but various different sensors
can be applied) 5002B is attached.
[0462] The object detecting sensor 5002B is aligned to a
sufficiently wide detection region including the target portion
5001A of the domestic animal 5001 that moves irregularly in the
floor F partitioned in all directions.
[0463] An image that is acquired by the object detecting sensor
5002B is input to a target recognizing unit 5002C of the controller
5003 and the target recognizing unit 5002C detects the position of
the target portion 5001A of the domestic animal 5001 and inputs the
detection result as the target position to an operation instructing
unit 5005 to be described below in real time.
[0464] In this embodiment, in order to simplify the description,
the controller 5003 is illustrated as one control device. However,
in actuality, the controller 5003 is configured using plural
computers and the target recognizing unit 5002C or an external
force detecting unit (to be described below) may be configured
using a control device that is separated from the robot controller
to control an operation of the robot arm 5002.
[0465] Each of the first to seventh actuators 5041A to 5047A is
composed of a decelerator-integrated servo motor that has a hollow
portion where a cable (not illustrated in the drawings) can be
inserted, and the rotation positions of the actuators are input as
signals from encoders incorporated in the actuators to the
controller 5003 through the cable.
[0466] As illustrated in FIG. 44, the sensor unit 5004 includes a
sensor fixing jig 5015 and four sensors S1 to S4 and the
disk-shaped sensor fixing jig 5015 is attached to an end of a
stator of the first actuator 5041A of the robot arm 5002.
[0467] Each of the sensors S1 to S4 (5016a to 5016d) is buried in
the disk-shaped sensor fixing jig 5015 and is disposed along the
same circle arc (virtual circle) at an equal interval. In each of
the sensors S1 to S4, quartz is used as a piezoelectric body. Each
of the sensors S1 to S4 detects the amount of strain of a radial
direction of the sensor fixing jig 5015 as a voltage, and the
obtained voltage is amplified by an amplifying unit 5017 and is
input to the controller 5003.
[0468] By a crystal oscillator (crystal piezoelectric element) in
each of the sensors S1 to S4, a response time is fast as compared
with the case where a strain gauge or other piezoelectric element
is used, superior responsiveness can be obtained as compared with
an operation cycle of a servo unit 5007 to be described below, and
the impact by a contact of an object existing around the robot arm
can be sufficiently alleviated.
[0469] In this embodiment, as described above, the crystal
oscillator is used because the response time is fast. However, any
device may be applied to each of the sensors S1 to S4, as long as
the superior responsiveness is obtained. In the crystal
piezoelectric sensor, durability is superior as compared with the
strain gauge or a common collision sensor and high-precision
detection is enabled even when the sensor unit 5004 is provided in
a base end where a load based on the self weight of the robot arm
5002 is largest.
[0470] An operation of driving portions that include the actuators
5041A to 5047A of the robot arm 5002 is controlled by the
controller 5003.
[0471] The controller 5003 is composed of a computer that includes
a storage device, an electronic operator, and an input device (all
of which are not illustrated in the drawings), and is connected to
each driving portion of the robot arm 5002 to communicate with each
other.
[0472] As illustrated in FIG. 42, the controller 5003 has a target
recognizing unit 5002C, an operation instructing unit 5005, a
smoothing processing unit 5006, a servo unit 5007, a contact
detecting unit (external force detecting unit) 5008, a position
instruction intercepting unit (operation instruction intercepting
unit) 5009, an external force direction detecting unit 5010, an
avoidance axis selecting unit 5011, an avoidance compensating unit
(friction compensation torque adding unit) 5012, a gravity torque
compensating unit (gravity compensation torque adding unit) 5013,
and a torque limiting unit 5014 as components.
[0473] As described above, the target recognizing unit 5002C
calculates the position of the target portion 5001A of the domestic
animal 5001, on the basis of the detection result of the object
detecting sensor 5002B, and the position of the target portion
5001A is transmitted as the target position to the operation
instructing unit 5005.
[0474] As a method that recognizes the position of the target
portion 5001A by the target recognizing unit 5002C, various methods
may be applied.
[0475] The operation instructing unit 5005 calculates a position
instruction (operation instruction) with respect to each of the
actuators Ac5041 to Ac5047, on the basis of the input of the target
position from the target recognizing unit 5002C, and pools the
position instruction to the smoothing processing unit 5006.
[0476] In the smoothing processing unit 5006, the pooled position
instruction is sequentially given to the side of the servo unit
5007 for every operation cycle T (mm/sec).
[0477] The servo unit 5007 has a joint angle feedback circuit Fp
based on a detection value of the encoder of each of the actuators
5041A to 5047A and a joint angle feedback circuit Fv based on an
angular speed detection value obtained from the detection value of
the encoder of each of the actuators 5041A to 5047A, for each of
the actuators Ac1001 to Ac1015. The servo unit 5007 outputs the
torque instruction Tref for every operation cycle T.
[0478] The contact detecting unit 5008 detects whether the domestic
animal 5001 and the robot arm 5002 contact, on the basis of an
output of the sensor unit 5004.
[0479] The configuration of the contact detecting unit 5008 will be
described in detail. As illustrated in FIG. 45, the contact
detecting unit 5008 has a high-pass filter unit 5018 and a
threshold value determining unit 5019.
[0480] The high-pass filter unit 5018 has high-pass filters (or
band-pass filters) F1 to F4 that extract only high frequency
components with respect to the sensor signals from the amplifying
units 5017 of the sensor units 5004, and separates a signal
component due to the external force and transmits the signal
component to the external force direction detecting unit 5010.
[0481] With respect to adjustment of each of the high-pass filters
F1 to F4, a contact experiment (for example, the robot arm is beat
by a hammer) is performed in advance, a frequency of a detection
signal of each of the sensors S1 to S4 when the external force is
generated by a contact is measured, and a cutoff frequency of each
filter is determined to remove a frequency component other than the
frequency due to the external force.
[0482] In this way, a signal component included in the detection
signal of each of the sensors S1 to S4 due to a factor of
disturbance generated in the robot arm 5002, such as a ripple of a
decelerator incorporated in each of the actuators 5041A to 5047A,
and a signal component due to the external force based on a contact
with a peripheral object or the robot arm can be separated from
each other.
[0483] The threshold value determining unit 5019 determines whether
an absolute value of the detection signal (after passing through
the high-pass filters F1 to F4) of each of the sensors S1 to S4
exceeds a predetermined threshold value (adjusted by a collision
experiment). When an absolute value of any one of the detection
signals of the sensors S1 to S4 exceeds the threshold value, the
threshold value determining unit 5019 determines that the contact
is generated (external force is generated).
[0484] When it is detected by the threshold value determining unit
5019 that the contact is generated, the position instruction
intercepting unit 5009 (refer to FIG. 42) is operated, transmission
of the position instruction from the operation instructing unit
5005 to the smoothing processing unit 5006 is intercepted, the
position instruction that is transmitted to the servo unit 5007 is
decreased by the smoothing processing unit 5006, and transmission
of the position instruction with respect to the servo unit 5007 is
intercepted.
[0485] If the transmission of the position instruction with respect
to the servo unit 5007 is intercepted, a value of the torque
instruction Tref that is output by the feedback decreases and the
robot arm 5002 is quickly stopped.
[0486] As illustrated in FIG. 46, the external force direction
detecting unit 5010 has a peak calculating unit 5020, a
positive/negative determining unit 5021, and a table referring unit
5022 as components.
[0487] The peak calculating unit 5020 calculates a peak value of an
impact wave, with respect to a detection signal for each of the
sensors S1 to S4 output from the high-pass filter unit 5018. The
peak value is a maximum value of an absolute value of the detection
signal (that is, maximum value in predetermined time).
[0488] The positive/negative determining unit 5021 outputs
positive/negative (1 or -1) or zero of each peak value to be
calculated.
[0489] That is, when the absolute value of the peak value is less
than the predetermined threshold value, the positive/negative
determining unit 5021 outputs zero (determination
impossibility).
[0490] The table referring unit 5022 calculates torque of a
direction where the external force generated by a contact of the
domestic animal 5001 is applied (external force direction torque),
by referring to a data table previously set to a storage device,
with respect to a combination of positive/negative of an impact
wave peak of each sensor signal.
[0491] The data table may be configured as a matrix in which the
combination of positive/negative of the detection signal for each
of the sensors S1 to S4 and the external force direction are
associated with each other, as illustrated in FIGS. 47 and 48.
[0492] As such, by referring to the data table and the combination
of the positive/negative of the detection signal for each of the
sensors S1 to S4, collision directions (in this embodiment, eight
directions) can be broadly calculated using the plural sensor
signals, from the positive/negative of the impact wave peak at the
time of colliding. Since the sensor unit 5004 is attached to the
side of the base 5040 of the robot arm 5002, the collision
directions can be calculated, even when the contact object such as
the domestic animal 5001 contacts the position of the side of the
base end as well as a peripheral portion of a front end of the
robot arm 5002.
[0493] As illustrated in FIG. 49, the avoidance axis selecting unit
5011 has a vector converting unit 5023 and a joint vector
positive/negative determining unit 5024 as components.
[0494] The vector converting unit 5023 multiplies an external force
direction vector described by work coordinates of the robot arm
5002 by a transposed matrix of a Jacobian matrix of the robot arm
5002 and converts the external force direction vector into a vector
for each of the actuators 5041A to 5047A.
[0495] In this case, since the robot arm 5002 is a redundant
manipulator, a vector of the actuator 5043A (redundant axis) can
set as zero.
[0496] The actuators 5041A and 5042A are set to a first axis and a
second axis, respectively, the actuators 5044A to 5047A are set to
the third to sixth axiss, and the external force direction vector
is converted into each axis vector. When the first to sixth axiss
are not specified, these axiss are simply called a axis.
[0497] As the Jacobian matrix, a Jacobian matrix with respect to a
wrist point of the robot arm 5002 may be calculated, because the
domestic animal 5001 and the robot arm 5002 are likely to contact
in the vicinity of a wrist of the robot arm 5002.
[0498] Instead of the transposed matrix, an inverse matrix may be
used. However, it is preferable to use the transposed matrix,
because a calculation load of the transposed matrix is smaller than
a calculation load of the inverse matrix.
[0499] The joint vector positive/negative determining unit 5024
outputs positive/negative (1 or -1) with respect to each component
(component of each joint axis) of the external force direction
vector converted in a joint space. When an absolute value is less
than the predetermined threshold value, the joint vector
positive/negative determining unit 5024 outputs zero.
[0500] As illustrated in FIG. 50, the avoidance compensating unit
5012 has a friction compensation vector calculating unit 5025 and a
friction compensation value storage unit 5026 as components.
[0501] The friction compensation vector calculating unit 5025
multiplies each component (.+-.1 or zero) of the external force
direction vector in each joint space output from the avoidance axis
selecting unit 5011 by a friction compensation value of each axis
and outputs a calculated value.
[0502] The friction compensation value of each axis is previously
adjusted and a determined value is stored in the friction
compensation value storage unit 5026.
[0503] When the corresponding axis is completely stopped, the
friction compensation value is calculated on the basis of a maximum
static friction torque of the actuator corresponding to the axis.
When the corresponding axis rotates, the friction compensation
value is calculated on the basis of a dynamic friction torque of
the actuator corresponding to the axis.
[0504] As illustrated in FIG. 42, the friction compensation vector
(torque) that is output from the avoidance compensating unit 5012
and the gravity compensation vector are added to the torque
instruction Tref in the servo unit 5007.
[0505] The gravity compensation torque is calculated by the gravity
torque compensating unit 5013. Hereinafter, a sum of the friction
compensation torque and the gravity compensation torque is called
an avoidance compensation torque Tavo.
[0506] A sum of the original torque instruction Tref that is output
from the feedback circuit of the servo unit 5007 and the avoidance
compensation torque Tavo is input to the torque limiting unit
5014.
[0507] An output of the avoidance axis selecting unit 5011 is input
to the torque limiting unit 5014 as well as the avoidance
compensating unit 5012. With respect to the axis where the output
of the avoidance axis selecting unit 5011 is +1 or -1, the torque
limiting unit 5014 limits a torque instruction value with respect
to the corresponding actuator.
[0508] As illustrated in FIG. 51, the torque limiting unit 5014
sets the torque instruction value with respect to the corresponding
actuator to be limited within a torque limitation width 27 (Wtrp)
previously calculated by an experiment, using the avoidance
compensation torque 26 (Tavo) as a center value. Therefore, a motor
torque is limited between the torque upper limit 28 (TU) and the
torque lower limit 29 (TL) and the limited torque is transmitted as
a final torque instruction value to each of the actuators 5041A to
5047A.
[0509] As described above, the avoidance compensation torque Tavo
is the torque to support each actuator by the robot arm 5002 with
respect to a moment load by the self weight and (gravity
compensation torque) and operate the robot arm 5002 in a direction
where the external force is applied with respect to the static
friction force or the dynamic friction force of the actuator
(friction compensation torque). For this reason, if a value of the
torque upper limit 28 (TU) is excessively large, generation of the
excessive torque is allowed to cause a load with respect to the
robot arm 5002.
[0510] Meanwhile, if a value of the torque lower limit 29 (TL) is
excessively small, the self weight is not supported and the joint
is unintentionally rotated by the gravity.
[0511] Therefore, by sufficiently decreasing the torque limitation
width Wtrp, the unnecessary force is not applied to the domestic
animal 5001, and each joint of the robot arm 5002 can be guided to
a direction where the impact or the external force based on the
collision is alleviated. The torque limitation value Wtrp is
preferably minimized (the difference of the torque upper limit TU
and the torque lower limit TL is small). However, the predetermined
gravity compensation torque or the predetermined friction
compensation torque do not necessarily become an optimal value and
may include an error. For this reason, in order to allow the error
of the predetermined gravity compensation torque or the
predetermined friction compensation torque, the torque limitation
width Wtrq that is previously obtained by an experiment needs to be
set. By setting the torque limitation width Wtrq, the robot arm
5002 can be stably controlled.
[0512] The torque may be limited immediately after the rotation
axis is selected and the avoidance compensation torque is
fixed.
[0513] Since the robot system according to this embodiment has the
above-described configuration, at the time of starting the work,
the robot system detects the position of the target portion 5001A
of the domestic animal 5001 at any time, on the basis of a
detection image from the object detecting sensor 5002B, provides
the detected position as the target position for every operation
cycle to the servo unit 5007, approaches the tool of the end
effector to the target portion 5001A even when the position of the
target portion 5001A is irregularly changed by the feedback
control, and performs the work such as such as inspection,
sterilization, and milking with respect to the target portion 5001A
of the domestic animal 5001.
[0514] When the domestic animal 5001 moves greatly at the time of
the work and contacts the robot arm 5002 and the contact (external
force) is detected by the contact detecting unit 5008, the position
instruction intercepting unit 5009 is operated and intercepts the
position instruction from the operation instructing unit 5005 such
that the position instruction is not transmitted to the servo unit
5007. Therefore, the robot arm 5002 is stopped.
[0515] At this time, since the instruction data held in the
smoothing processing unit 5006 is sequentially provided to the
servo unit 5007 as described above, generation of the impact by
rapid stop of the robot arm 5002 is reduced.
[0516] Meanwhile, a sensor output is transmitted from the contact
detecting unit 5008 to the external force detecting unit 5010 and
the external force direction detecting unit 5010 detects a
collision direction of the domestic animal 5001 and the robot arm
5002. The avoidance axis selecting unit 5011 selects a joint axis
of the robot arm 5002 to be avoided, on the basis of the detected
external force direction vector. The avoidance compensating unit
5012 performs operation compensation with respect to the selected
avoidance axis and alleviates the collision. The avoidance axis
selecting unit 5011 moves to the torque limiting unit 5014 to limit
the torque of the rotation axis.
[0517] Thereby, when the domestic animal 5001 and the robot arm
5002 contact, because the robot arm 5002 is actively avoided in an
external force direction with high responsiveness under a series of
control of the servo unit, the impact at the time of the contact
can be alleviated. Since the robot arm 5002 is stopped after being
avoided in the external force direction from the contact generation
position, the possibility of the domestic animal 5001 and the robot
arm 5002 continuously colliding can be lowered.
[0518] The torque limiting unit 5014 of the robot control device
for the domestic animal in this embodiment limits the avoidance
object axis within the torque limitation width Wtrq based on the
avoidance compensation torque. Therefore, even when the domestic
animal 5001 further moves to the side of the robot arm 5002, the
unnecessary force is not applied from the robot arm 5002 to the
domestic animal 5001 and the robot arm can be guided to a direction
where the impact force is alleviated. The excessive external force
is not applied to the domestic animal 5001 and the robot arm 5002
and safety is improved.
[0519] In the contact detecting unit 5008 according to this
embodiment, the high-pass filter unit 5018 extracts only the high
frequency vibration at the time of the collision from the output
signal of the sensor unit 5004. Therefore, even when the
disturbance such as the ripple of the decelerator is applied to the
sensor, the contact of the domestic animal 5001 and the robot arm
5002 can be detected at a high speed and with high sensitivity.
[0520] Since the avoidance compensating unit 5012 of the robot
control device for the domestic animal in this embodiment adds the
avoidance compensation torque to the torque instruction, a response
speed can be increased as compared with the case of the avoidance
and the compensation using the position instruction.
[0521] Next, a sixth embodiment will be described.
[0522] A robot system according to this embodiment is different
from the robot system according to the fifth embodiment in the
configuration of the controller 5003. Therefore, the same portions
as those of the fifth embodiment are denoted by the same reference
numerals and the overlapped description is omitted.
[0523] FIG. 52 is a block diagram illustrating the detailed
configuration of a contact detecting unit 5008 according to this
embodiment.
[0524] In this embodiment, the contact detecting unit 5008 has a
moving average filter unit 5030 between the high-pass filter unit
5018 and the threshold value determining unit 5019.
[0525] The moving average filter unit 5030 has first to fourth
moving average filters that output an average of sensor signals in
predetermined time going back from the present time, with respect
to the sensor signals output from the high-pass filter unit
5018.
[0526] By this configuration, when a disturbance signal such as a
servo noise having a frequency component equal to or higher than a
signal component of an impact wave passes through the high-pass
filters, only the disturbance signal is removed by the moving
average filter. As a result, in the case other than the collision,
erroneous detection of a contact by the threshold value determining
unit 5019 can be avoided. As described above, if the threshold
value determining unit 5019 detects the contact, the sensor signal
passing unit 5031 is operated at the same time as the operation of
the position instruction intercepting unit 5009, and the sensor
signal that is output from the high-pass filter unit 5018 is output
to the external force direction detecting unit 5010.
[0527] FIG. 53 is a block diagram illustrating the detailed
configuration of the external force direction detecting unit 5010
according to this embodiment.
[0528] A signal integrating unit 5032 calculates an integration
value of the sensor signals input until the present time, with
respect to the sensor signals output from the sensor signal passing
unit 5031 of FIG. 52. By using the integration value of the
signals, the positive/negative change of the signals is smoothened,
and certainty of identification of positive/negative at each time
is improved.
[0529] As an example of a signal integration processing result, a
signal 34 before the integration is input to the signal integrating
unit 5032 and a signal 35 after the integration is obtained, as
illustrated in FIG. 54. In the signal 35 after the integration, the
frequency in the change in the positive/negative becomes lower than
that of the signal 34 before the integration.
[0530] A narrowing condition referring unit 5033 calculates a
collision direction (external force direction vector) by referring
to a predetermined external force direction narrowing condition
table (data table), with respect to the positive/negative of each
signal integration value output by the positive/negative
determining unit 5021.
[0531] As illustrated in FIG. 55, the narrowing condition table is
data where the positive/negative of each of sensor signal
integration values at plural predetermined times and the external
force direction vector candidates are associated and is stored in
the storage device of the controller 5003.
[0532] In an example of FIG. 55, the narrowing condition table is
composed of a table at four times of X1 to X4
(X1<X2<X3<X4).
[0533] An arrangement relationship of the sensors S1 to S4 and the
external force direction vectors V1 to V8 is as illustrated in FIG.
48. The narrowing condition referring unit 5033 extracts the
external force direction vector candidates that satisfy a condition
with respect to positive/negative of each sensor signal integration
value at each time. For example, as illustrated in FIG. 56, the
case where the combination (negative, negative, positive, and
positive) of the positive/negative of the integration values of the
sensors S1 to S4 at the time X1 will be described.
[0534] When the integration value of the sensor S1 is negative, the
external force direction vector candidate becomes any one of the
external force direction vectors V1, V3, and V7. When the
integration value of the sensor S2 is negative, the external force
direction vector candidate becomes any one of the external force
direction vectors V1, V5, and V7. At this time, V1 and V7 become
both the external force direction vector candidates. Likewise, V1
and V7 become the external force direction vector candidates with
respect to the positive/negative of the integration values of the
sensors S3 and S4.
[0535] If the number of extracted external force direction vectors
is 1, the extraction result (external force direction vector) is
input to the avoidance axis selecting unit 5011. If the number of
external force direction vector candidates is 2 or more, the
external force direction vector candidates are calculated using
both the extraction result of the external force direction vector
candidates at the next time and the extraction result until the
current time.
[0536] In the case of the above example, the external force
direction vector is continuously extracted by referring to the
combination of the positive/negative of the integration values at
the next time X2 and the narrowing condition table. In this way,
narrowing is repeated until the number of external force direction
vector candidates becomes 1 or less. By using the sensor signals at
the plural times, a detection rate of an external force direction
can be improved. When the number of external force direction vector
candidates becomes 0 by narrowing or the number of external force
direction vector candidates is 2 or more in the case of referring
to all of the tables until the predetermined narrowing end time, it
is determined that the external force direction is uncertain, and
all elements of the external force direction vectors are set to
zero and are input to the avoidance axis selecting unit 5011.
[0537] Since the robot system according to this embodiment has the
above-described configuration, the disturbance that passes through
the high-pass filter unit 5018 and is generated in very short time
is suppressed by the moving average filter unit 5030, and erroneous
detection of contact generation performed by the contact detecting
unit 5008 when the object such as the domestic animal and the robot
arm 5002 do not contact is suppressed.
[0538] The external force direction detecting unit 5010 decreases
the frequency in the change in the positive/negative of the signal
by the signal integrating unit 5032 and certainty of the
identification of the positive/negative at each time is improved.
Since the narrowing condition referring unit 5033 refers to the
sensor signals at the plural times, the detection rate of the
external force direction is improved.
[0539] Next, a seventh embodiment will be described.
[0540] A robot system according to this embodiment is different
from the robot system according to the fifth embodiment in the
configuration of the controller 5003. Therefore, the same portions
as those of the fifth embodiment are denoted by the same reference
numerals and the overlapped description is omitted.
[0541] As illustrated in FIG. 57, this embodiment is different from
the fifth embodiment in that an operation instruction returning
unit 5038 is provided as a component of the controller 5003.
[0542] The operation instruction returning unit 5038 releases
interception of a position instruction by the position instruction
intercepting unit 5009, when the contact detecting unit 5008 does
not newly detect the external force within a predetermined period
(for example, in predetermined time after a collision avoidance
operation), in a state in which the contact detecting unit 5008
detects a contact and a position instruction from the operation
instructing unit 5005 is intercepted, and the position instruction
from the operation instructing unit 5005 is transmitted to the side
of the servo unit 5007 through the smoothing processing unit
5006.
[0543] Since the robot system according to the seventh embodiment
has the above-described configuration, the robot system previously
sets a predetermined period to an optimal value by an experiment.
When the domestic animal 5001 and the robot arm 5002 contact during
the operation of the robot arm 5002, the robot arm performs an
avoidance operation in an external force application direction
during the predetermined period and an excessive contact of the
domestic animal 5001 and the robot arm 5002 can be prevented. After
the predetermined period passes, because the approaching operation
with respect to the target portion 5001A is restarted on the basis
of the detection result of the object detecting sensor 5002B, even
though the contact is generated, the robot arm 5002 is not stopped
or the robot arm is stopped in a short time, and the work such as
the inspection, the sterilization, and the milking with respect to
the domestic animal 5001 can be continuously performed.
[0544] That is, it is preferable to stably perform the work with
respect to the work object (or position target of the robot)
without stopping the work, while a slight contact of the robot arm
5002 and the object existing around the robot arm is allowed,
according to an application purpose of the robot system 5100.
[0545] In the case of this embodiment, for example, work efficiency
may be greatly lowered, if the robot arm 5002 is stopped, whenever
the domestic animal 5001 moves with the high frequency and
frequently contacts the robot arm 5002. However, if the
predetermined period is set, when the domestic animal 5001 and the
robot arm 5002 contact, the work is continuously performed by the
robot arm 5002 while the robot arm 5002 is made to execute the
avoidance operation in the external force direction and the
excessive external force (or impact) is suppressed, and work
efficiency can suppressed from being lowered due to the
contact.
[0546] The fifth to seventh embodiments have been described.
However, the embodiment may be implemented by various different
embodiments other than the fifth to seventh embodiments. Therefore,
the various different embodiments are hereinafter described as
modifications.
[0547] For example, in the above embodiment, the four crystal
piezoelectric sensors are buried as the sensor unit 5004 in the
sensor fixing jig of the base of the robot. However, the number of
sensors may be 3 or less or five or more. The sensors are buried in
the sensor fixing jig. However, the sensors may be attached to a
surface of the robot. Alternatively, sensor elements other than the
crystal piezoelectric sensor may be used.
[0548] The maximum number of times of narrowing the external force
direction is 4. However, the maximum number of times of narrowing
the external force direction may be 3 or less or 5 or more.
[0549] The above embodiment is not limited to the case where the
work is performed with respect to the domestic animal and may be
applied to various purposes. For example, the above embodiment may
be applied to a control device in the case where a human being and
a robot perform work in cooperation with each other.
[0550] Next, an eighth embodiment will be described.
[0551] In a multiple joint robot, it may be required to control a
robot having a degree of freedom (redundant degree of freedom)
higher than a degree of freedom of the required position/posture.
That is, since the robot has the redundant degree of freedom, the
posture of the manipulator can be variously changed even though the
required position/posture is taken with respect to the object.
Therefore, by appropriately controlling the redundant degree of
freedom, the work can be performed while interference with the
manipulator or the object existing around the manipulator is
avoided at the time of the work in a relatively narrow place.
Japanese Patent Application Laid-Open (JP-A) No. 2007-203380
discloses a method that controls the manipulator having the
redundant degree of freedom.
[0552] Meanwhile, a large number of manipulators are operated along
a previously instructed operation path. According to an application
purpose, the work may be performed with respect to a work object
where the position is uncertain, such as a moving work object. In
this case, the target position/posture of the manipulator is
modified on the basis of information of a sensor to detect the
position of the work object. Thereby, the work can be performed
with respect to the work object while the manipulator follows the
work object.
[0553] However, in the case where the manipulator has the redundant
degree of freedom, in the method in the related art that determines
the operation amounts of all of the driving axiss including the
redundant degree of freedom by the instruction in advance, when the
position of the work object is moved as described above, the
position of the redundant degree of freedom does not become
necessarily the appropriate position, and interference (contact)
with the work object or the manipulator is generated.
[0554] The instructed operation path may be changed according to
the work object, the manipulator unintentionally may take the
singular posture, and a problem may be generated in control of the
manipulator.
[0555] This problem is generated in the case where an obstacle
existing in an operation range of the manipulator moves, the case
where an unintentional contact with the manipulator and an object
existing around the manipulator is generated, and the case where an
operation orbit of the manipulator is changed, in addition to the
case where the target position/posture is changed on the basis of
the sensor.
[0556] According to one aspect of an embodiment, a robot system and
a robot control device that can optimally control a manipulator
having a redundant degree of freedom are provided.
[0557] According to this embodiment, even when the targeted
position/posture is changed, a redundant axis of the manipulator
can be appropriately set with the small operation amount, and the
manipulator having the redundant degree of freedom can be optimally
controlled.
[0558] Hereinafter, an eighth embodiment will be described with
reference to the drawings. This embodiment is an example of the
case where the robot system disclosed in the present application is
applied to a robot system to perform work such as inspection,
sterilization, and milking for a domestic animal, using a
manipulator 6002.
[0559] As illustrated in FIG. 58, a robot system 6100 according to
this embodiment includes a floor F that receives a domestic animal
6001, a manipulator 6002, a controller 6003, and a sensor unit
6004.
[0560] As illustrated in FIG. 59, in the manipulator 6002, a base
6040 that is fixed to a mounting surface (wall surface or floor)
6101 and a first structural material 6041, a second structural
material 6042, a third structural material 6043, a fourth
structural material 6044, a fifth structural material 6045, a sixth
structural material 6046, and a flange 6047 that are disposed
sequentially from the base 6040 to a front end of the manipulator
6002 are connected through actuators (rotation joint) that are
driven to rotate.
[0561] The base 6040 and the first structural material 6041 are
connected through a first actuator (first joint) 6041A and the
first structural material 6041 is rotated by driving of the first
actuator 6041A. The first structural material 6041 and the second
structural material 6042 are connected through a second actuator
(second joint) 6042A and the second structural material 6042 is
rotated by driving of the second actuator 6042A.
[0562] The second structural material 6042 and the third structural
material 6043 are connected through a third actuator (third joint)
6043A and the third structural material 6043 is rotated by driving
of the third actuator 5043A.
[0563] The third structural material 6043 and the fourth structural
material 6044 are connected through a fourth actuator (fourth
joint) 6044A and the fourth structural material 6044 is rotated by
driving of the fourth actuator 6044A.
[0564] The fourth structural material 6044 and the fifth structural
material 6045 are connected through a fifth actuator (fifth joint)
6045A and the fifth structural material 6045 is rotated by driving
of the fifth actuator 6045A. The fifth structural material 6045 and
the sixth structural material 6046 are connected through a sixth
actuator (sixth joint) 6046A and the sixth structural material 6046
is rotated by driving of the sixth actuator 6046A.
[0565] The sixth structure 6046 and the flange 6047 are connected
through a seventh actuator (seventh joint) 6047A, and the flange
6047 and an end effector 6002A such as a hand that is attached to
the flange 6047 are rotated by driving of the seventh actuator
6047A.
[0566] In this embodiment, the third actuator (third joint) 6043A
is previously stored as a redundant axis in a storage region of the
controller 6003 (redundant axis setting unit) and the rotation
position of the third actuator 6043A is optimally controlled by a
function of the controller 6003 to be described below. The actuator
6043A is called the redundant axis, the actuators 6041A and 6042A
are called a first axis and a second axis, respectively, and the
actuators 6044A to 6047A are called third to sixth axiss,
respectively. When the first to sixth axiss are not specified,
these axiss are simply called a axis.
[0567] Various tools (not illustrated in the drawings) such as an
inspector, a milker, and a sterilizer are attached to the end
effect 6002A and performs work such as inspection, sterilization,
and milking, with respect to a target portion 6001A of the domestic
animal 6001. In the case of the manipulator 6002 according to this
embodiment, a control point that is the position to control the
operation position of the manipulator 6002 is set as a point where
the manipulator can be linearly moved by driving of each of the
actuators 6044A to 6047A and is positioned in the vicinity of a
axis center of the sixth actuator 6046A.
[0568] A position relationship of the control point, and the flange
6047, and the end effector 6002A and each tool is previously input
to the controller 6003 and the position of each tool can be
controlled by controlling the position/posture of the control
point.
[0569] To the end effector (that is, front end of the robot arm
6002) 6002A, an object detecting sensor (in this embodiment, the
object detecting sensor is a camera, but various different sensors
can be applied) 6002B is attached.
[0570] The object detecting sensor 6002B is aligned to a
sufficiently wide detection region including the target portion
6001A of the domestic animal 6001 that moves irregularly in the
floor F partitioned in all directions.
[0571] An image that is acquired by the object detecting sensor
6002B is input to the target position/posture generating unit 6010
of the controller 6003 and the target position/posture generating
unit 6010 detects the position of the target portion 6001A of the
domestic animal 6001 and inputs the detection result as the target
position to a simulation unit 6005 to be described below in real
time.
[0572] In this embodiment, in order to simplify the description,
the controller 6003 is illustrated as one control device. However,
in actuality, the controller 6003 is configured using plural
computers and the target position/posture generating unit 6010 or
an external force detecting unit (to be described below) may be
configured using a control device that is separated from the robot
controller to control an operation of the manipulator 6002.
[0573] Each of the first to seventh actuators 6041A to 6047A is
composed of a decelerator-integrated servo motor that has a hollow
portion where a cable (not illustrated in the drawings) can be
inserted, and the rotation positions of the actuators are input as
signals from encoders incorporated in the actuators to the
controller 6003 through the cable.
[0574] As illustrated in FIG. 60, the sensor unit 6004 includes a
sensor fixing jig 6025 and four sensors S1 to S4 and the
disk-shaped sensor fixing jig 6025 is attached to a base of a
stator of the first actuator 6041A of the manipulator 6002.
[0575] Each of the sensors S1 to S4 is buried in the disk-shaped
sensor fixing jig 6025 and are disposed along the same circle arc
(virtual circle) at an equal interval. In each of the sensors S1 to
S4, quartz is used as a piezoelectric body. Each of the sensors S1
to S4 detects the amount of strain of a radial direction of the
sensor fixing jig 6025 as a voltage, and the obtained voltage is
amplified by an amplifying unit (not illustrated in the drawings)
and is input to the controller 6003.
[0576] By a crystal oscillator (crystal piezoelectric element) in
each of the sensors S1 to S4, a response time is fast as compared
with the case where a strain gauge or other piezoelectric element
is used, superior responsiveness can be obtained as compared with
an operation cycle of a servo control unit 6014 to be described
below, and impact based on a contact of an object existing around
the manipulator can be sufficiently alleviated.
[0577] In this embodiment, as described above, the crystal
oscillator is used because the response time is fast. However, any
device may be applied to each of the sensors S1 to S4, as long as
the superior responsiveness is obtained. In the crystal
piezoelectric sensor, durability is superior as compared with the
strain gauge or a common collision sensor and high-precision
detection is enabled even when the sensor unit 6004 is provided in
a base end where a load based on the self weight of the manipulator
6002 is largest.
[0578] An operation of driving portions that include the actuators
6041A to 6047A of the manipulator 6002 is controlled by the
controller 6003.
[0579] The controller 6003 is composed of a computer that includes
a storage device, an electronic operator, and an input device (all
of which are not illustrated in the drawings), and is connected to
each driving portion of the manipulator 6002 to communicate with
each other.
[0580] As illustrated in FIG. 58, the controller 6003 has a
simulation unit 6005, a redundant angle definition table generating
unit 6006, a redundant angle definition table 6007, a table
display/input unit 6008, a target position/posture generating unit
6010, a region determining unit 6011, a redundant axis angle
setting unit 6012, an interpolation operating unit 6013, a servo
control unit 6014, an amplifying unit 6015, and an external force
detecting unit (avoidance operation executing unit) 6016 as
components.
[0581] The simulation unit 6005 is configured to generate an
operation trace from the current position/posture to the target
position/posture, on the basis of information of the position of an
obstacle in an operation enabled region of the manipulator to be
input in advance, the target position/posture of a control point
from the target position/posture generating unit 6010, and the
current position/posture of the manipulator 6002 obtained from a
detection signal of an encoder of each of the actuators 6041A to
6047A. As an algorism for generating the operation trace, various
algorithms may be applied.
[0582] The operation trace may be generated by the simulation unit
6005 at the time of an instruction operation of the manipulator
6002. At the time of an automatic operation, a redundant angle may
be determined by referring to the redundant angle definition table
6007. By alleviating the load of a CPU, a solution (target position
instruction with respect to each of the actuators 6041A to 6047A)
can be determined at practical time.
[0583] On the basis of the input information from the table
display/input unit 6008, as illustrated in FIG. 61, the redundant
angle definition table generating unit 6006 divides a region 6101
of a three-dimensional space previously set in the operation region
of the manipulator 6002 according to a previously executed
experiment in consideration of the operation of the manipulator
6002 and an object existing around the manipulator or the domestic
animal 6001, and sets divided small regions.
[0584] The region 6101 and the small regions (m, n, l) are
associated with a simultaneous transformation matrix with a
reference coordinate system .SIGMA.w of the manipulator 6002, with
respect to a reference coordinate system .SIGMA.c. The region 6101
is previously divided into L small regions in a Z direction, N
small regions in a Y direction, and M small regions in an X
direction, on the basis of the experiment result described
above.
[0585] Specifically, the redundant angle definition table
generating unit 6006 determines the size of the region 6101,
according to the variation of the solid of the domestic animal 6001
(for example, the variation of the position of the target portion
6001A or the variation of the position of an obstacle such as legs
of the domestic animal 6001). That is, when the variation is large,
the region 6101 is set to have a large size, and when the variation
is small, the region 6101 is set to have a small size.
[0586] Each of the divided small regions Sc (m, n, l) are set to
become a rectangular solid. A shape of the small regions Sc (m, n,
l) is preferably rectangular, because the operation amount can be
suppressed. However, various shapes may be set according to
necessity.
[0587] In the redundant angle definition table 6007, a parameter to
set the position of a redundant axis with respect to each region of
the divided region 6101 is associated.
[0588] Information of the region 6101, that is, information of
positions, dimensions, and shapes of the small regions Sc (m, n, l)
and information of the parameters corresponding to the information
are displayed on a display device by processing of the table
display/input unit 6008 an the information can be input/modified by
a worker using the input device.
[0589] The target position/posture generating unit 6010 is
configured to generate the targeted position/postures of various
tools griped by the end effector 6002A of the manipulator 6002, on
the basis of input information from the object detecting sensor
6002B and input information from the external force detecting unit
6016 to be described below.
[0590] Meanwhile, when the external force detecting unit 6016
detects the external force, the target position/posture generating
unit 6010 temporarily stops an operation based on the detection
result of the object detecting sensor 6002B and sets the newest
target position/posture including a contact avoiding correction
value of the target position/posture input from the external force
detecting unit 6016 as the target position/posture.
[0591] The region determining unit 6011 selects the small region S
of the redundant angle definition table 6007 from the small regions
Sc (m, n, l), on the basis of the output of the target
position/posture generating unit 6010 and the output of the
redundant angle definition table 6007.
[0592] When it is determined that the small corresponding to the
output of the target position/posture generating unit 6010 does not
exist in the small regions Sc (m, n, l), the region determining
unit 6011 outputs an abnormal signal to the object detecting sensor
6002B, and avoidance work such as focal adjustment is executed at
the side of the object detecting sensor 6002B.
[0593] Alternatively, When it is determined that the small
corresponding to the output of the target position/posture
generating unit 6010 does not exist in the small regions Sc (m, n,
l), an error warning message may be displayed by a display device
of the controller 6003.
[0594] The redundant axis angle setting unit 6012 sets the angle
(target position) of the redundant axis, on the basis of the
parameter of the redundant angle definition table 6007
corresponding to the region selected by the region determining unit
6011.
[0595] The interpolation operating unit 6013 performs an
interpolation operation with respect to an operation aspect (or
including the operation speed) of each of the actuators 6041A to
6047A until the target position/posture from the current position
where an inverse kinematics operation is not executed, on the basis
of the angular position of the third actuator 6043A to be the
redundant axis set by the redundant axis angle setting unit 6012
and the operation trace calculated by simulation unit 6005, and
outputs the target position instruction of each of the actuators
6041A to 6047A for every predetermined operation cycle.
[0596] The servo control unit 6014 performs the position speed
feedback control, on the basis of the target position instruction
of each of the actuators 6041A to 6047A output from the
interpolation operating unit 6013 for every predetermined operation
cycle and an input signal from an encoder of each of the actuators
6041A to 6047A.
[0597] The amplifying unit 6015 performs operation control of each
of the actuators 6041A to 6047A, on the basis of the operation
instruction output from the servo control unit 6014.
[0598] The external force detecting unit 6016 detects whether the
external force is generated with respect to the manipulator 6002,
on the basis of the input signal from each of the sensors S1 to S4,
calculates a contact avoiding correction value of the target
position to make the manipulator 6002 avoid the external force, and
inputs the correction value to the side of the target
position/posture generating unit 6010.
[0599] Since the robot system 6100 according to the eighth
embodiment has the above-described configuration, at the time of
starting the work, the object detecting sensor 6002B measures the
position of the target portion 6001A of the domestic animal 6001,
the measurement result is input to the controller 6003, and the
target position/posture of the control point is calculated by the
target position/posture generating unit 6010.
[0600] The measurement information that is obtained from the object
detecting sensor 6002B is three position information of X, Y, and Z
of translational degrees of freedom of 3. Operational degrees of
freedom of the manipulator 6002 are 7 and redundant degrees of
freedom are 4.
[0601] For this reason, in order to generate the target
position/posture of degrees of freedom of 6 that is the sum of
rotational degrees of freedom of 3 and translational degrees of
freedom of 3 on the basis of the detection information of the
object detecting sensor 6002B according to this embodiment, the
target portion 6001A is assumed as a nipple of the domestic animal,
and the nipple has a cylindrical shape. As illustrated in FIG. 62,
since a shape is constant around a Z'' axis and the target portion
6001A is downward, a rotation angle around Y'' and X'' axes is
assumed as a constant angle, and the target position/posture
generating unit 6010, the region determining unit 6011, and the
redundant axis angle setting unit 6012 determines Rz (rotation
position around the Z'' axis) and an elbow angle Ex using the
redundant angle definition table 6007.
[0602] That is, the position and the coordinates (Xs, Ys, Zs) of
the target portion 6001A based on the object detecting sensor
coordinate system that are calculated by the object detecting
sensor 6002B are input to the region determining unit 6011, and a
number of the corresponding small region is determined from the
small regions Sc (m, n, l), by referring to the redundant angle
definition table 6007 illustrated in FIG. 63.
[0603] For example, if a region No2 is selected in FIG. 63, as
values of Rz and Ex, 47 and 75 are set by the redundant axis angle
setting unit 6012. The set position and posture angle are input to
the interpolation operating unit 6013, a target position
instruction with respect to each of the actuators 6041A to 6047A is
generated on the basis of inverse kinematics and is input to the
servo control unit 6014 and the amplifying unit 6015, and the
manipulator 6002 positions the target portion 6001A in the target
portion 6001A (refer to FIG. 62). The above operation is
repetitively executed for each sampling cycle of a measurement
frequency (for example, 100 Hz or more) of the object detecting
sensor 6002B.
[0604] An operation cycle of the position speed feedback control in
the servo control unit 6014 is shorter than the sample cycle.
[0605] As such, according to the robot system according to this
embodiment, the target position/posture is calculated fro each
operation cycle, on the basis of the detection result input from
the object detecting sensor 6002B for each measurement frequency,
and the angular position of the redundant axis is set from the
collation result with the redundant angle definition table 6007, on
the basis of the target position/posture. Therefore, the redundant
axis of the manipulator can be appropriately set with the small
operation amount, and the manipulator having the redundant degree
of freedom can be optimally controlled.
[0606] Thereby, even when the manipulator 6002 is operated in a
narrow work space where a moving obstacle such as the leg of the
domestic animal 6001 exists, the posture of the redundant axis can
be changed according to the position of the target portion 6001A,
and high work efficiency can be maintained by reducing the contact
probability of the manipulator 6002 and the obstacle.
[0607] Even when the manipulator 6002 and the obstacle contact,
because the target position/posture to avoid the external force is
changed by the external force detecting unit (avoidance operation
executing unit) 6016, the manipulator 6002 does not excessively
contact the obstacle and can avoid the obstacle. The angular
position of the redundant axis is set from the collation result
with the redundant angle definition table 6007, on the basis of the
modified target position/posture, at the time of the contact
avoidance operation. Therefore, the posture of the manipulator 6002
can be appropriately controlled to reduce the contact probability
with another obstacle, during the avoidance operation of the
obstacle.
[0608] The eighth embodiment has been described. However, the
embodiment may be implemented by various different embodiments
other than the eighth embodiment. Therefore, the various different
embodiments are hereinafter described as modifications.
[0609] The embodiment is not limited to the case where the work is
performed with respect to the domestic animal and can be applied to
various different purposes. For example, the embodiment can be
applied to the case where the position of the obstacle in the
operation range of the manipulator is changed.
[0610] In the above embodiment, the manipulator of the degree of
freedom of 7 that has the seven actuators is described. However,
the degree of freedom of the manipulator is not limited thereto and
this embodiment can be applied to the manipulator having the degree
of freedom of 8 or more by appropriately setting data of the
redundant angle definition table.
[0611] In the case of the manipulator having the degree of freedom
of 6 or less, when the degree of freedom of 1 or more is allowed
with respect to an approach with respect to the work object, the
manipulator has a redundant degree of freedom. However, this
embodiment can be applied to the above case.
[0612] According to at least one embodiment described above,
functionality of the robot can be improved.
[0613] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
[0614] In regard to the embodiments, the following aspects are
disclosed.
Note 1. A robot comprising:
[0615] a robot arm;
[0616] one or more actuators that are provided in the robot arm and
drive the robot arm;
[0617] a sensor fixing jig that is provided in a base of the
actuator, among the actuators in the robot arm, closest to a base
end of the robot arm; and
[0618] a strain sensor that is provided in the sensor fixing jig
and has a piezoelectric body with a natural frequency higher than a
natural frequency of a structural material forming the robot
arm.
Note 2. The robot of Note 1,
[0619] wherein the sensor fixing jig is provided in a casing of the
robot arm or a casing of the robot.
Note 3. The robot of Note 1 or 2,
[0620] wherein at least three strain sensors are provided in the
sensor fixing jig.
Note 4. The robot of Note 3,
[0621] wherein the at least three strain sensors are radially
disposed on the same circumference at an equal interval.
Note 5. The robot of any one of Notes 1 to 4,
[0622] wherein the sensor fixing jig is formed in an annular
circular shape with an opening at the center.
Note 6. The robot of any one of Notes 1 to 5,
[0623] wherein the strain sensor is a sensor that uses quartz as
the piezoelectric body.
Note 7. A robot comprising:
[0624] a robot arm that includes one or more actuators; and
[0625] a first strain sensor that is provided in the vicinity of a
front end of a casing of the robot arm and has a piezoelectric body
with a natural frequency higher than a natural frequency of a
structural material forming the robot arm.
Note 8. The robot of Note 7, further comprising:
[0626] an A/D converter that is provided in the vicinity of the
first strain sensor and converts an output signal of the first
strain sensor into a digital signal.
Note 9. The robot of Note 7 or 8,
[0627] wherein the first strain sensor is provided on an external
surface of the casing.
Note 10. The robot of any one of Notes 7 to 9, further
comprising:
[0628] a second strain sensor that is provided in a base of the
actuator, among the actuators in the robot arm, closest to a base
end of the robot arm and has a piezoelectric body with a natural
frequency higher than a natural frequency of the structural
material.
Note 11. The robot of any one of Notes 7 to 10,
[0629] wherein each of the first strain sensor and the second
strain sensor is a sensor that uses quartz as the piezoelectric
body.
Note 12. A robot system comprising:
[0630] a robot that includes a robot arm;
[0631] a strain sensor that has a piezoelectric body with a natural
frequency higher than a natural frequency of a structural material
forming the robot arm; and
[0632] a control unit that includes a determining unit configured
to determine whether the robot is in a normal state or an abnormal
state, on the basis of an output value of the strain sensor.
Note. 13 The robot system of Note 12,
[0633] wherein the control unit has a normative data recording unit
that records a time history of the output value of the strain
sensor while the robot arm executes a predetermined operation at
the time of the normal state as normative data, and
[0634] the determining unit determines whether the robot is in the
normal state or the abnormal state by comparing output data of the
output value of the strain sensor at timing when the robot arm
executes the predetermined operation at the time of activating and
with the normative data recorded in the normative data recording
unit.
Note 14. The robot system of Note 13,
[0635] wherein the determining unit determines that the robot is in
the normal state, when the difference of the output data and the
normative data is within a range of a predetermined threshold
value, and determines that the robot is in the abnormal state, when
the difference exceeds the threshold value.
Note 15. The robot system of Note 14,
[0636] wherein the control unit further includes a threshold value
setting unit that sets the threshold value.
Note 16. The robot system of any one of Notes 13 to 15,
[0637] wherein the control unit further includes a section setting
unit that sets a section which is a subject for which the time
history of the output value of the strain sensor is recorded by the
normative data recording unit as the normative data.
Note. 17 The robot system of 16,
[0638] wherein the control unit further includes a zero point
adjusting unit that adjusts a zero point of the strain sensor,
whenever the robot arm executes the predetermined operation
corresponding to the section set by the section setting unit.
Note 18. The robot system of any one of Notes 13 to 17,
[0639] wherein the control unit further includes a high-pass filter
unit that extracts a high frequency vibration component of the
output signal of the strain sensor, and
[0640] the determining unit compares the normative data based on
the high frequency vibration component extracted by the high-pass
filter unit with the output data, and determines whether the robot
is in the normal state or the abnormal state.
Note 19. The robot system of any one of Notes 13 to 18,
[0641] wherein the control unit further includes a low-pass filter
unit that extracts a low frequency vibration component of the
output signal of the strain sensor, and
[0642] the determining unit compares the normative data based on
the low frequency vibration component extracted by the low-pass
filter unit with the output data, and determines whether the robot
is in the normal state or the abnormal state.
Note 20. The robot system of any one of Notes 12 to 19,
[0643] wherein the strain sensor is a sensor that uses quartz as
the piezoelectric body.
Note 21. A state determining method of a robot that determines
whether the robot including a robot arm is in a normal state or an
abnormal state, the method comprising:
[0644] an output value acquiring sequence that acquires an output
value of a strain sensor having a piezoelectric body with a natural
frequency higher than a natural frequency of a structural material
forming the robot arm; and
[0645] a determining sequence that determines whether the robot is
in the normal state or the abnormal state, on the basis of the
output value of the strain sensor.
Note 22. The state determining method of Note 21, further
comprising:
[0646] a normative data recording sequence that records a time
history of the output value of the strain sensor while the robot
arm executes a predetermined operation at the time of the normal
state as normative data,
[0647] wherein the determining sequence compares output data of the
output value of the strain sensor when the robot arm executes the
predetermined operation at the time of activating with the recorded
normative data, and determines whether the robot is in the normal
state or the abnormal state.
Note 23. A robot system comprising:
[0648] a robot including a robot arm; and
[0649] a control unit that controls the robot,
[0650] wherein the robot includes a strain sensor provided in the
robot arm, and
[0651] wherein the control unit includes: [0652] a normative data
recording unit that records a time history of an output value of
the strain sensor while the robot arm executes a predetermined
operation in a state in which there is no abnormality in the robot
arm as normative data; [0653] an output data recording unit that
records a time history of an output value of the strain sensor
while the robot arm executes the predetermined operation at the
time of activating as output data; and [0654] a
comparing/determining unit that compares the normative data
recorded in the normative data recording unit with the output data
recorded in the output data recording unit and determines whether
there is abnormality in the robot arm. Note 24. The robot system of
Note 23,
[0655] wherein one or more actuators that operate one or more joint
portions of the robot arm are provided in the robot arm, and
[0656] the comparing/determining unit determines that there is
abnormality in the actuators, when an event that the difference
between the output data and the normative data exceeds a
predetermined threshold value occurs for every predetermined
cycle.
Note 25. The robot system of Note 23 or 24,
[0657] wherein the comparing/determining unit determines that there
is abnormality in the robot arm, when the number of times of excess
where the difference between the output data and the normative data
exceeds the predetermined threshold value in a predetermined time
period, exceeds a predetermined number of times of
determination.
Note 26. The robot system of Note 25,
[0658] wherein the comparing/determining unit performs
determination while changing the number of times of determination
according to an operation speed of the robot arm.
Note 27. The robot system of Note 25 or 26,
[0659] wherein the control unit further includes a threshold value
setting unit that sets the threshold value.
Note 28. The robot system of any one of Notes 23 to 27,
[0660] wherein the control unit further includes a section setting
unit that sets a section that is a subject for which the time
history of the output value of the strain sensor is recorded by the
normative data recording unit as the normative data.
Note 29. The robot system of Note 28,
[0661] wherein the control unit further includes a zero point
adjusting unit that adjusts a zero point of the strain sensor,
whenever the robot arm executes the predetermined operation
corresponding to the section set by the section setting unit.
Note 30. The robot system of any one of Notes 23 to 29,
[0662] wherein the control unit further includes a high-pass filter
unit that extracts a high frequency vibration component of the
output signal of the strain sensor, and
[0663] the comparing/determining unit compares the normative data
based on the high frequency vibration component extracted by the
high-pass filter unit with the output data, and determines whether
the robot is in the normal state or the abnormal state.
Note 31. The robot system of any one of Notes 23 to 30,
[0664] wherein the strain sensor is a force sensor that has a
piezoelectric body with a natural frequency higher than a natural
frequency of a structural material forming the robot arm.
Note 32. The robot system of Note 31,
[0665] wherein the strain sensor is a sensor that uses quartz as
the piezoelectric body.
Note 33. An abnormality detecting method of a robot that determines
whether there is abnormality in a robot arm included in the robot,
the abnormality detecting method comprising:
[0666] a normative data recoding sequence that records a time
history of an output value of a strain sensor provided in the robot
arm while the robot arm executes a predetermined operation in a
state in which there is no abnormality as normative data;
[0667] an output data recording sequence that records the time
history of the output value of the strain sensor while the robot
arm executes the predetermined operation at the time of activating
as output data; and
[0668] a comparing/determining sequence that compares the normative
data with the output data, and determines whether there is
abnormality in the robot arm.
Note 34. A robot system comprising:
[0669] a robot arm;
[0670] one or more actuators that are provided in the robot arm and
drive the robot arm;
[0671] a sensor unit that detects the external force applied to at
least one of the robot arm and the actuator; and
[0672] a controller that controls an operation of the actuator and
limits a torque instruction value with respect to the actuator, on
the basis of the detection result of the sensor unit.
Note 35. The robot system of Note 34, further comprising:
[0673] a position sensor that detects a position and a posture of a
control point inside the robot arm or the actuator, the control
point being a point where the position and the posture are
controlled by the controller,
[0674] wherein the controller includes: [0675] an operation
instruction setting unit that sets the position of each actuator
corresponding to the position and the posture of the control point,
as the target position, and sets an operation instruction with
respect to each actuator,
[0676] a servo unit that generates a torque instruction with
respect to each actuator, for every predetermined operation cycle,
on the basis of at least the operation instruction and the
detection result of the position sensor,
[0677] an external force detecting unit that detects a direction of
the external force when the external force is generated, on the
basis of the detection result of the sensor unit,
[0678] an avoidance axis selecting unit that selects the actuator
to perform an avoidance operation from among the one or more
actuators, on the basis of the direction of the external force
detected by the external force detecting unit,
[0679] a gravity compensation torque adding unit that adds the
gravity compensation torque corresponding to the self weight to the
torque instruction generated by the servo unit, and
[0680] a friction compensation toque adding unit that adds the
friction compensation torque to cause the actuator to operate in
the direction of the external force against the friction force of
the actuator, to the torque instruction generated by the servo unit
with respect to the actuator selected by the avoidance axis
selecting unit.
Note 36. The robot system of Note 35,
[0681] wherein the controller includes an operation instruction
intercepting unit that intercepts the operation instruction given
to the servo unit, when the external force is detected by the
external force detecting unit.
Note 37. The robot system of Note 36,
[0682] wherein the controller includes an operation instruction
returning unit that releases the interception of the operation
instruction by the operation instruction intercepting unit, when
the external force is not detected by the external force detecting
unit during a predetermined period or more after the operation
instruction is intercepted by the operation instruction
intercepting unit.
Note 38. The robot system of any one of Notes 35 to 37,
[0683] wherein the controller includes a torque instruction
limiting unit that limits a torque instruction value with respect
to the actuator, and
[0684] the torque instruction limiting unit sets an upper limit and
a lower limit of the torque instruction value, on the basis of the
sum of the gravity compensation torque and the friction
compensation torque.
Note 39. The robot system of any one of Notes 35 to 38,
[0685] wherein the sensor unit includes plural sensors that use
quartz as the piezoelectric body.
Note 40. The robot system of Note 39,
[0686] wherein the sensor unit includes: a disk-shaped sensor
fixing jig provided in a base of the actuator, among the actuators
in the robot arm, closest to a base end of the robot arm, and
[0687] the plural sensors buried in the sensor fixing jig along the
same circular arc.
Note 41. The robot system of Note 40,
[0688] wherein the external force detecting unit extracts a high
frequency vibration component of each signal from the plural
sensors and detects whether the external force is generated, on the
basis of the extracted high frequency vibration components.
Note 42. The robot system of Note 41,
[0689] wherein the external force detecting unit calculates a peak
value of the extracted high frequency vibration component for each
sensor and detects a direction of the external force on the basis
of a combination of positives and negatives of the peak values of
the sensors.
Note 43. The robot system of Note 42,
[0690] wherein the avoidance axis selecting unit executes threshold
value processing on each component of a vector obtained through a
calculation of multiplying a direction vector of the external force
calculated by the external force detecting unit by a transposed
matrix of a Jacobian matrix and calculates an avoidance object
joint axis and a direction.
Note. 44 The robot system of Note 43,
[0691] wherein the friction compensation torque adding unit adds a
maximum static friction torque of the actuator as the friction
compensation torque, when the actuator selected by the avoidance
axis selecting unit is stopped, and adds a dynamic friction torque
of the actuator as the friction compensation torque, when the
actuator rotates.
Note 45. The robot system of Note 41,
[0692] wherein the external force detecting unit detects whether
the external force is generated, on the basis of a moving average
obtained by executing moving averaging processing on the extracted
high frequency vibration component for each sensor.
Note. 46 The robot system of Note 41,
[0693] wherein the external force detecting unit calculates an
integration value of the high frequency vibration component for
each sensor after the generation of the external force is detected,
and detects a direction of the external force on the basis of a
combination of positives and negatives of the integration
values.
Note 47. The robot system of Note 45 or 46,
[0694] wherein the controller includes a data table where a
combination of positives and negatives of the integration values of
the sensors or a combination of positives and negatives of the
moving averages of the sensors and the direction of the external
force are associated with each other, and
[0695] the external force detecting unit detects the direction of
the external force, on the basis of the combination of the
positives and negatives of the integration values of the sensors or
the combination of the positives and negatives of the moving
averages of the sensors, at a plurality of timings after the
generation of the external force is detected.
Note 48. A control device of a robot including a robot arm with one
or more actuators, and a sensor unit detecting an external force
applied to at least one of the robot arm and the actuators, the
control device comprising:
[0696] an actuator control unit that transmits a torque instruction
to the actuator; and
[0697] a torque instruction limiting unit that limits a value of
the torque instruction transmitted to the actuator, on the basis of
an input which is the result from the sensor unit.
Note 49. A robot system comprising:
[0698] a manipulator that includes one or more actuators; and
[0699] a controller that controls an operation of each of the
actuators,
[0700] wherein the controller includes: [0701] a redundant axis
setting unit that sets a part of the actuators as a redundant
axis,
[0702] a target position/posture generating unit that sets a target
position/posture of the manipulator,
[0703] a simulation unit that generates an operation trace until
the manipulator reaches from the current posture to the target
position/posture, on the basis of the target position/posture,
[0704] a redundant angle definition table in which small regions
set by dividing a region in a movable range of the manipulator and
parameters for redundant axis angles corresponding to the small
regions are associated with each other,
[0705] a region determining unit that selects the corresponding
small region in the redundant angle definition table, on the basis
of the result output from the target position/posture generating
unit,
[0706] a redundant axis angle setting unit that sets the redundant
axis angle, on the basis of the selection result of the region
determining unit and the redundant angle definition table, and
[0707] an interpolation operating unit that generates an operation
instruction with respect to each of the actuators, on the basis of
the operation trace and the redundant axis angle.
Note 50. The robot system of Note 49, further comprising:
[0708] an object detecting sensor that detects the position of a
work object,
[0709] wherein the target position/posture generating unit changes
the target position/posture, on the basis of the detection result
of the object detecting sensor.
Note 51. The robot system of Note 49 or 50, further comprising:
[0710] a sensor unit that detects the external force applied to the
manipulator,
[0711] wherein the controller includes an avoidance operation
executing unit that controls an operation of the actuator and
causes the actuator to execute an avoidance operation in an
avoidance direction with respect to the external force, on the
basis of the detection result of the sensor unit.
Note 52. The robot system of any one of Notes 49 to 51,
[0712] wherein the controller has a table display/input unit that
displays the redundant angle definition table and receives a
modification of contents of the redundant angle definition
table.
Note 53. The robot system of any one of Notes 49 to 52,
[0713] wherein the manipulator includes:
[0714] a base,
[0715] a first joint that causes a first structural material to
operate relative to the base,
[0716] a second joint that causes a second structural material to
operate relative to the first structural material,
[0717] a third joint that causes a third structural material to
operate relative to the second structural material,
[0718] a fourth joint that causes a fourth structural material to
operate relative to the third structural material,
[0719] a fifth joint that causes a fifth structural material to
operate relative to the fourth structural material,
[0720] a sixth joint that causes a sixth structural material to
operate relative to the fifth structural material, and
[0721] a seventh joint that causes a flange to rotate relative to
the sixth structural material.
Note 54. The robot system of any one of Notes 49 to 53,
[0722] wherein each of the small regions that are defined in the
redundant angle definition table has a shape of a rectangular
parallelepiped.
Note 55. The robot system of any one of Notes 50 to 54,
[0723] wherein each of the small regions that are defined in the
redundant angle definition table are set in advance, taking a
variation in the position of the work object into
consideration.
Note 56. The robot system of any one of Notes 50 to 55,
[0724] wherein the region determining unit outputs an abnormal
signal to the object detecting sensor, when it is determined that
the corresponding small region in the redundant angle definition
table does not exist, from the output result of the target
position/posture generating unit.
Note 57. A robot control device that controls an operation of a
manipulator having one or more actuators, the robot control device
comprising:
[0725] a redundant axis setting unit that sets a part of the
actuators to a redundant axis,
[0726] a target position/posture generating unit that sets a target
position/posture of the manipulator,
[0727] a simulation unit that generates an operation trace until
the manipulator reaches from the current posture to the target
position/posture, on the basis of the target position/posture,
[0728] a redundant angle definition table in which small regions
set by dividing a region in a reachable range of the manipulator
and parameters for redundant axis angles corresponding to the small
regions are associated with each other,
[0729] a region determining unit that selects the corresponding
small region in the redundant angle definition table, on the basis
of the output result of the target position/posture generating
unit,
[0730] a redundant axis angle setting unit that sets the redundant
axis angle, on the basis of the selection result of the region
determining unit and the redundant angle definition table, and
[0731] an interpolation operating unit that generates an operation
instruction with respect to each of the actuators, on the basis of
the operation trace and the redundant axis angle.
* * * * *